Name: High-throughput Screening for Protein-based Inheritance in S. cerevisiae (Video) | JoVE Journal
Uploaded: 2017-08-08T14:00:00.000+00:00
Duration: 8 min 12 s
Description: Learn high-throughput screening for protein-based inheritance in S. cerevisiae using unbiased phenotypic memory assays. This method enables researchers to identify prion-like proteins and study epigenetic mechanisms in yeast.

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5 minutes

We thank Sohini Chakrabortee, Sandra Jones, David Garcia, Bhupinder Bhullar, Amelia Chang, Richard She, and Susan Lindquist for their assistance in developing the assays used in this paper, as well as the reviewers for their thoughtful comments.

1. Initial Overexpression
<ol>
	<li>Transform the yeast cells (in this case, BY4741 MAT a haploids) previously grown in YPD liquid (10 g of yeast extract, 20 g of peptone, and 20 g of glucose per 1 L) with the desired candidate constructs from the FLEXGene ORFeome library (yeast ORFs under the control of a galactose-inducible promoter in the URA3-marked centromericplasmid backbone, pBY01129).</li>
	<li>Use autoclaved toothpicks to pick four separate colonies from these transformations to serve as biological replicates. Grow them for 48-72 h in 150 &#181;L of SRaffinose-URA (0.74 g of CSM-URA, 6.7 g of yeast nitrogen base without amino acids, and 20 g of raffinose per 1 L) in 96-well plates. Inoculate colonies from the first ORF in well A1 of all plates, colonies from the second ORF in A2 of all plates, etc. 
	NOTE: All growth steps are conducted at 30 &#176;C and at atmospheric levels of CO2 (407.05 ppm), unless stated otherwise.</li>
	<li>Confirm that the cultures are saturated (cells visible by eye at the bottom of each well) and use a liquid handling robot to inoculate a 1:4 array of 1 &#181;L from each 96-well plate well into 4 separate wells of a 384-well plate filled with 45 &#181;L of SGal-URA (0.74 g of CSM-URA, 6.7 g of yeast nitrogen base without amino acids, and 20 g of galactose per 1 L) per well. 
	NOTE: This creates a composite plate in which 4 biological replicates of each ORF are arrayed in a square pattern.</li>
	<li>At the same time, prepare separate 384-well plates containing 45 &#181;L of SGal-URA with the stressors of interest (e.g., manganese chloride at 20 mM) per well. Inoculate this plate in the same manner as in step 1.3. 
	NOTE: To achieve the greatest dynamic range for phenotypic detection, a 2-fold dilution series around the LD50 concentration of a given stressor is recommended. This can be done beforehand to determine the optimum concentration at which to observe both enhanced and reduced growth.</li>
	<li>As a final parallel control, inoculate a third 384-well plate in the same manner, with the same stressor included in medium that will not induce plasmid expression. Ensure that the plate contains 45 &#181;L of SD-URA (0.74 g of CSM-URA, 6.7 g of yeast nitrogen base without amino acids, and 20 g of glucose per 1 L) per well and is inoculated as in steps 1.3 and 1.4.</li>
	<li>Immediately place plates with cells on a microplate stacker and set the protocol for a 72-h continuous loop, measuring the OD600 with a microplate reader equipped with stackers at room temperature and atmospheric CO2 (407.05 ppm). 
	Note: The frequency of the growth measurement will depend on the number of plates (ultimately determined by the number of genes and conditions the investigator wants to probe) used in the run. The more plates used, the longer it will take the plate reader to complete a loop and thus the longer time between measurements (measurement time per plate is ~45 s, depending on the instrumentation employed).</li>
	<li>After the growth measurements, use the same liquid handling robot to transfer 1 &#181;L per well of the SGal-URA-induced cultures (i.e., those that experienced protein overexpression) to new 384-well plates containing 45 &#181;L of SD-URA per well (medium that does not permit protein expression of the plasmid).
	<ol>
		<li>In parallel, perform analogous inoculations of a second set of 384-well plates containing 45 &#181;L of SD-URA per well from the cultures that were grown in SD-URA in the presence of the stressors (i.e., those from step 1.5).</li>
		<li>Grow the plates for 48 h at 30 &#176;C to saturation in a humidified chamber (i.e., a sealable plastic bin with a damp paper towel inside).</li>
	</ol>
	</li>
	<li>Take the plates from the previous step and reinoculate 1 &#181;L per well in 384-well plates containing 45 &#181;L of SD-URA. Then, perform a separate reinoculation of 1 &#181;L per well from the same source plate into a separate 384-well plate containing 45 &#181;L of SD-URA with the stressor. 
	NOTE: This will determine if the sensitivity/resistance phenotypes to a stressor persist after the protein overexpression has ceased.</li>
	<li>Immediately place plates with cells on a microplate stacker and set the protocol for a 48-h continuous loop measuring the OD600 with a microplate reader at room temperature and atmospheric CO2 (407.05 ppm).</li>
	<li>Export the time versus OD600 measurements as an XY table using the plate reader software. Group columns of the OD600 for each biological replicate together and calculate the mean. Create an XY plot of time versus OD600 to generate growth curves.
	<ol>
		<li>Compare the growth rates of cultures that had been subjected to a past overexpression (i.e., those originally induced in galactose-containing medium before reinoculation in SD-URA) versus cultures that had not (i.e., those propagated in glucose), as described previously30.</li>
	</ol>
	</li>
	<li>For cultures that show significant growth differences in response to a given stressor, dependent upon ancestral protein overexpression, take 1 &#181;L from each biological replicate, dilute it in 10 mL of water, and then plate 50 &#181;L on plates containing 5-FOA (0.74 g of CSM-URA, 1 g of 5-FOA, 50 mg of uracil, 6.7 g of yeast nitrogen base without amino acids, 20 g of glucose, and 20 g of agar per liter). Grow at 30 &#176;C for 3 days.
	<ol>
		<li>If this results in too many or too few colonies per plate, adjust the dilution factor accordingly. 
		Note: 5-FOA is converted into a toxic intermediate by the uracil biosynthesis pathway. This will cause a loss of the URA3-marked expression plasmid transformed in the first step.</li>
	</ol>
	</li>
	<li>Pick 8-32 single colonies with autoclaved toothpicks and pin them to 96-well plates containing 150 &#181;L of SD-CSM. Grow to saturation for 48-72 h in a humidified chamber at 30 &#176;C. Use these cultures to inoculate two new sets of 96-well plates containing 150 &#181;L of SD-CSM, both with and without the stressors from step 1.11.</li>
	<li>Place the plates on a microplate stacker and set the protocol to measure the OD600 on a 48-h continuous loop.</li>
	<li>Analyze the data as in step 1.10 and confirm that the significant growth differences seen in step 1.10 are maintained after plasmid loss. 
	NOTE: These cells harbor stable phenotypic states that might be indicative of protein-based inheritance.</li>
	<li>Test the cells that maintained the induced phenotypes for classic hallmarks of protein-based inheritance (see below).</li>
</ol>
2. Tests for Prion-like Inheritance
<ol>
	<li>Chaperone-mediated &#34;curing&#34;
	<ol>
		<li>Test Hsp104 chaperone dependence.
		<ol>
			<li>Pick a colony of a yeast strain harboring a stable phenotypic state, streak to single colonies on a YPD plate (10 g of yeast extract, 20 g of peptone, 20 g of glucose, and 20 g of agar per 1 L) containing 3 mM GdnHCl and grow at 30 &#176;C for 3 days. In parallel, streak out a colony from a na&#239;ve strain to single colonies on YPD+ 3 mM GdnHCl as a control in the same manner.</li>
			<li>Repeat 2 more times on fresh YPD plates containing 3 mM GdnHCl.</li>
			<li>Because GdnHCl exposure can increase the frequency at which petite cells arise, pick multiple colonies that have undergone 3 passages on GdnHCl and check for functional mitochondrial respiration by examining their ability to grow into visible colonies on YP-Glycerol plates (10 g of yeast extract, 20 g of peptone, 20 mL of glycerol, and 20 g of agar per 1 L) after 7 days.</li>
			<li>Pick multiple colonies from the YP-Glycerol plates and test for the maintenance of stable phenotypic states using growth in the presence of the stressor compared to non-&#34;cured&#34; and na&#239;ve (i.e., isogenic cells that do not harbor the phenotypic state, such as BY4741 MATa haploids) controls in a similar manner as described in step 1.13.</li>
		</ol>
		</li>
		<li>Test Hsp70 chaperone dependence.
		<ol>
			<li>&#34;Cure&#34; via a plasmid.
			<ol>
				<li>Transform both na&#239;ve cells and cells harboring stable phenotypic states with URA3-marked plasmids expressing a dominant negative allele of Hsp70 (K69M)25,31 from a strong constitutive promoter (GPD).</li>
				<li>Pick single transformants for each, streak to single colonies on an SD-URA plate (0.74 g of CSM-URA, 6.7 g of yeast nitrogen base without amino acids, 20 g of glucose, and 20 g of agar per 1 L), and grow for 3 days at 30 &#176;C and atmospheric CO2.</li>
				<li>Repeat this passaging 2 more times on SD-URA plates.</li>
				<li>Pick multiple colonies and streak to single colonies on 5-FOA plates to eliminate the plasmid.</li>
				<li>Pick multiple single colonies for each isolate and test for retention (or loss) of the stable phenotypic states in a similar manner as described in step 1.13.</li>
			</ol>
			</li>
			<li>&#34;Cure&#34; via genetic crossing.
			<ol>
				<li>Cross BY4741 MATa haploid strains harboring stable phenotypic states and na&#239;ve strains of the opposite mating type (in this case, BY4742 MAT&#945;) harboring genetic deletions in two of the four yeast Hsp70 paralogs (ssa1&#916; ssa2&#916;). 
				NOTE: This strain is deficient in Hsp70 chaperone function.</li>
				<li>Select for the growth of diploids by streaking to single colonies on SD-LYS-MET (0.74 g of CSM-LYS-MET, 6.7 g of yeast nitrogen base without amino acids, 20 g of glucose, and 20 g of agar per 1 L) double-dropout medium.</li>
				<li>Pick single diploid colonies and grow for 24 h at 30 &#176;C in 8 mL of pre-sporulation medium (0.8% yeast extract, 0.3% peptone, 10% dextrose, and 100 mg/L adenine sulfate).</li>
				<li>Spin down the cultures for 3 min at 3,000 xg, aspirate the pre-sporulation (pre-SPO) medium, and wash the pellets once with sterile water.</li>
				<li>Re-suspend the pellets in 2 mL of sporulation medium (1% potassium acetate, 0.1% yeast extract, 0.05% glucose, and 0.01% amino acid add-back mix (2 g of histidine, 10 g of leucine, 2 g of lysine, and 2 g of uracil)). Grow at 25&#176;C for 5 days.</li>
				<li>Move the cultures to 30 &#176;C and incubate for an additional 48 h.</li>
				<li>Assess the efficiency of sporulation by looking for the presence of tetrads using a light microscope32.</li>
				<li>Take 40 &#181;L of culture, spin down for 1 min at 3,000 xg in a 1.5-mL tube, and re-suspend in an equal volume of zymolyase enzyme mix (1 M sorbitol, 0.1 M EDTA, and 10 mg/mL zymolyase 100T)</li>
				<li>Incubate at 25 &#176;C for 5 min.</li>
				<li>Apply 10 &#181;L of digested culture to a very dry, very level YPD agar plate and allow the culture to slowly spread down the plate in a straight line.</li>
				<li>Allow the plates to dry for at least 30 min in a laminar flow hood.</li>
				<li>Using a dissection microscope, separate the spores into tetrads and array them on the plate.</li>
				<li>Allow the individual haploid spores to grow into colonies and test for their ability to grow on SD-HIS-LEU (0.67 g of CSM-HIS-LEU, 6.7 g of yeast nitrogen base without amino acids, 20 g of glucose, and 20 g of agar per 1L) plates, indicating that they harbor both genetic deletions (ssa1&#916; ssa2&#916;).</li>
				<li>Test each for the maintenance of the phenotypic state in the Hsp70-deficient background in a similar manner as described in step 1.13. 
				NOTE: Crossing these spores back to a wildtype strain with restored Hsp70 function should not restore the prion phenotype.</li>
			</ol>
			</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Testing for non-Mendelian inheritance.
	<ol>
		<li>Cross BY4741 MATa haploid strains harboring stable phenotypic states and isogenic na&#239;ve controls to an isogenic na&#239;ve strain of the opposite mating type (in this case, BY4742 MAT&#945;).</li>
		<li>Select for the growth of diploids by streaking to single colonies on SD-LYS-MET double-dropout medium.</li>
		<li>Pick single diploid colonies and grow for 24 h at 30 &#176;C in 8 mL of pre-sporulation medium.</li>
		<li>Repeat steps 2.2.2.3-2.2.2.12, as described above.</li>
		<li>Allow the individual haploid spores to grow into colonies and test each for maintenance of the phenotypic state through meiosis using the growth assay, as in step 1.13. 
		Note: Another defining feature of prions is that they can be heritably eliminated through the removal of the original casual protein. Thus, analogously crossing a prion strain with a strain harboring a genetic deletion of the original induced protein will abrogate prion phenotypes in the spores that inherit the deletion. Also note that is possible for the prion to be maintained in a &#34;cryptic&#34; state in such a mutant if the deleted gene is required to manifest the prion phenotype but not to propagate the prion itself. To distinguish between these two possibilities, cross the spores back to a na&#239;ve wildtype strain and test whether the prion phenotype re-emerges in a diploid genetic background, where the function of the gene has been restored.</li>
	</ol>
	</li>
	<li>Cytoduction.
	<ol>
		<li>Generate the initial BY4742 recipient strain.
		<ol>
			<li>Through transformation, introduce a defective KAR allele (kar1-15) that prevents nuclear fusion during mating23.</li>
			<li>Make this strain &#34;petite&#34; (i.e., incompetent for mitochondrial respiration) by inoculating a single colony in YPD broth with 0.25% ethidium bromide.</li>
			<li>Grow the culture at 30 &#176;C until late exponential/stationary phase (OD600 ~1).</li>
			<li>Dilute 1:1,000 in fresh YPD with 0.25% ethidium bromide and repeat twice.</li>
			<li>Once the culture reaches late exponential/early stationary phase (OD600 0.8-1.2), plate to single colonies by diluting 1:10,000 in sterile water and plating 50 &#181;L on a YPD plate. After growing for 3 days at 30 &#176;C, pick multiple colonies and test each for respiration incompetence by examining their ability to grow into visible colonies on YP-Glycerol plates after 7 days.</li>
		</ol>
		</li>
		<li>Perform initial cytoduction into BY4742.
		<ol>
			<li>Mix cells of the donor BY4741 strain harboring a stable phenotypic state with cells of the na&#239;ve BY4742 kar1-15 recipient strain on the surface of a YPD agar plate.</li>
			<li>Grow for 24 h at 30 &#176;C and atmospheric CO2 (407.05 ppm) and transfer to methionine dropout medium containing glycerol (SGly-MET: 0.74 g of CSM-MET, 6.7 g of yeast nitrogen base without amino acids, 20 mL of glycerol, and 20 g of agar per 1 L). 
			NOTE: This selects for both BY4742 nuclear markers, along with allowing the restoration of functional mitochondria via cytoplasmic exchange.</li>
			<li>After 3-5 days, pick multiple single colonies and perform another round of selection on SD-MET (0.74 g of CSM-MET, 6.7 g of yeast nitrogen base without amino acids, 20 g of glucose, and 20 g of agar per 1 L).</li>
			<li>In parallel, confirm that the colonies are not diploids by passaging on SD-LYS-MET medium.</li>
		</ol>
		</li>
		<li>Perform reverse cytoductions.
		<ol>
			<li>Mix the new donor strains (this time, the successful BY4742 kar1-15 cytoductants) with petite na&#239;ve BY4741 cells (generated as above) on YPD agar.</li>
			<li>Repeat cytoductions, as described previously (steps 2.3.2.1-2.3.2.4), except selecting for BY4741 recipient nuclear markers on glycerol medium lacking lysine (SGly-LYS: 0.74 g of CSM-LYS, 6.7 g of yeast nitrogen base without amino acids, 20 mL of glycerol, and 20 g of agar per 1 L).</li>
			<li>Pick multiple cytoductants and test for the maintenance of stable phenotypic states using the growth assay, as before in step 1.13.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Protein transformation.
	<ol>
		<li>Prepare the lysate.
		<ol>
			<li>Grow 50 mL of cells harboring stable phenotypic states in YPD for 18 h at 30 &#176;C.</li>
			<li>Pellet the cultures at 3,000 x g for 4 min and then wash twice: once in autoclaved H2O and then in 1 M sorbitol.</li>
			<li>Re-suspend the cells in 200 mL of SCE buffer (1 M sorbitol, 10 mM EDTA, 10 mM DTT, 100 mM sodium citrate, and 1 mini-EDTA-free protease inhibitor tablet per 50 mL, pH 5.8) with 50 U/mL of yeast lytic enzyme 100T.</li>
			<li>Incubate the mix at 35 &#176;C for 30 min.</li>
			<li>Sonicate the cells at 20 kHz and 20% intensity for 10 s on ice with a sonic dismembrator.</li>
			<li>Remove the cell debris by centrifugation at 10,000 x g for 15 min at 4 &#176;C.</li>
			<li>Move the supernatants to a clean tube and add RNase I and biotinylated DNase at a 3-fold excess (as determined by units of activity) and incubate at 37 &#176;C for 1 h.</li>
			<li>Remove the DNase I by adding excess streptavidin-agarose beads, incubating for 5 min, and pelleting by centrifugation at 10,000 x g for 1.5 min.</li>
			<li>Transfer the supernatant to a fresh tube.</li>
		</ol>
		</li>
		<li>Prepare the recipient spheroplast.
		<ol>
			<li>Grow 5 mL of na&#239;ve recipient cells in YPD to mid-exponential phase (OD600 ranging from 0.5-1).</li>
			<li>Harvest by centrifugation (3,000 x g for 4 min) and wash 4 times: twice in H2O and twice in 1 M sorbitol.</li>
			<li>Re-suspend the cells in 1 M sorbitol containing 200 U/mL yeast lytic enzyme and incubate for 15 min at 35 &#176;C to digest the cell walls.</li>
			<li>Harvest the resulting spheroplasts with gentle centrifugation at 600 x g for 5 min and wash with 1 mL of 1 M sorbitol and then again with 1 mL of STC buffer (1 M sorbitol, 10 mM Tris pH 7.5, and 10 mM CaCl2).</li>
			<li>Resuspend the washed spheroplasts in 50 &#181;L of STC buffer. 
			NOTE: Use scissors to cut off the last ~0.7 cm of a pipette tip; this will create a wider mouth and prevent the lysis of the spheroplasts.</li>
		</ol>
		</li>
		<li>Transform the na&#239;ve cells with protein.
		<ol>
			<li>Transform 50 &#181;L of spheroplast aliquots with 50 &#181;L of donor lysate, 20 &#181;L of salmon sperm DNA (2 mg/mL), and 5 &#181;L of a URA3-marked selection plasmid (e.g., pAG426-GFP)28,33.</li>
			<li>Incubate the mix at 25 &#176;C for 30 min.</li>
			<li>Centrifuge for 5 min at 600 x g to collect the spheroplasts and re-suspend in 150 &#181;L of SOS-buffer (1 M sorbitol, 7 mM CaCl2, 0.25% yeast extract, and 0.5% peptone).</li>
			<li>Recover for 30 min at 30 &#176;C.</li>
			<li>Plate the entire culture on SD-URA plates.</li>
			<li>Quickly overlay the plated culture with warm (~45 &#176;C) SD-URA containing 0.8% agar. 
			Note: This will prevent the spheroplasts from bursting</li>
			<li>Incubate the transformation plates for 2-3 days at 30 &#176;C.</li>
			<li>Using a toothpick, pick successfully growing cells from the overlaid plate and re-streak to single colonies on SD-URA plates.</li>
			<li>Pick dozens of colonies for each and streak on 5-FOA plates to eliminate URA3-marked carrier plasmid.</li>
			<li>Pick colonies that grow on the 5-FOA plates and test for the transfer of stable phenotypic states using the growth assay, as before (step 1.13).</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

<ol><li>Halfmann, R., Alberti, S., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prions%2C+protein+homeostasis%2C+and+phenotypic+diversity%5BTitle%5D)+AND+%22Trends+Cell+Biol%22%5BJournal%5D)">Prions, protein homeostasis, and phenotypic diversity.</a> Trends Cell Biol. 20 (3), 125-133 (2010).</li>
<li>Byers, J. S., Jarosz, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pernicious+pathogens+or+expedient+elements+of+inheritance%3A+the+significance+of+yeast+prions%5BTitle%5D)+AND+%22PLoS+Pathog%22%5BJournal%5D)">Pernicious pathogens or expedient elements of inheritance: the significance of yeast prions.</a> PLoS Pathog. 10 (4), 1003992(2014).</li>
<li>Jarosz, D. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cross-kingdom+chemical+communication+drives+a+heritable%2C+mutually+beneficial+prion-based+transformation+of+metabolism%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Cross-kingdom chemical communication drives a heritable, mutually beneficial prion-based transformation of metabolism.</a> Cell. 158 (5), 1083-1093 (2014).</li>
<li>True, H. L., Lindquist, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+yeast+prion+provides+a+mechanism+for+genetic+variation+and+phenotypic+diversity%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">A yeast prion provides a mechanism for genetic variation and phenotypic diversity.</a> Nature. 407 (6803), 477-483 (2000).</li>
<li>Suzuki, G., Shimazu, N., Tanaka, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+yeast+prion%2C+Mod5%2C+promotes+acquired+drug+resistance+and+cell+survival+under+environmental+stress%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">A yeast prion, Mod5, promotes acquired drug resistance and cell survival under environmental stress.</a> Science. 336 (6079), 355-359 (2012).</li>
<li>Hou, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((MAVS+forms+functional+prion-like+aggregates+to+activate+and+propagate+antiviral+innate+immune+response%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">MAVS forms functional prion-like aggregates to activate and propagate antiviral innate immune response.</a> Cell. 146 (3), 448-461 (2011).</li>
<li>Cai, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prion-like+polymerization+underlies+signal+transduction+in+antiviral+immune+defense+and+inflammasome+activation%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Prion-like polymerization underlies signal transduction in antiviral immune defense and inflammasome activation.</a> Cell. 156 (6), 1207-1222 (2014).</li>
<li>Majumdar, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Critical+role+of+amyloid-like+oligomers+of+Drosophila+Orb2+in+the+persistence+of+memory%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Critical role of amyloid-like oligomers of Drosophila Orb2 in the persistence of memory.</a> Cell. 148 (3), 515-529 (2012).</li>
<li>Khan, M. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Amyloidogenic+Oligomerization+Transforms+Drosophila+Orb2+from+a+Translation+Repressor+to+an+Activator%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Amyloidogenic Oligomerization Transforms Drosophila Orb2 from a Translation Repressor to an Activator.</a> Cell. 163 (6), 1468-1483 (2015).</li>
<li>Fioriti, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+Persistence+of+Hippocampal-Based+Memory+Requires+Protein+Synthesis+Mediated+by+the+Prion-like+Protein+CPEB3%5BTitle%5D)+AND+%22Neuron%22%5BJournal%5D)">The Persistence of Hippocampal-Based Memory Requires Protein Synthesis Mediated by the Prion-like Protein CPEB3.</a> Neuron. 86 (6), 1433-1448 (2015).</li>
<li>Derkatch, I. L., Bradley, M. E., Hong, J. Y., Liebman, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prions+affect+the+appearance+of+other+prions%3A+the+story+of+%5BPIN%28%2B%29%5D%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Prions affect the appearance of other prions: the story of [PIN(+)].</a> Cell. 106 (2), 171-182 (2001).</li>
<li>Alberti, S., Halfmann, R., King, O., Kapila, A., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+systematic+survey+identifies+prions+and+illuminates+sequence+features+of+prionogenic+proteins%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">A systematic survey identifies prions and illuminates sequence features of prionogenic proteins.</a> Cell. 137 (1), 146-158 (2009).</li>
<li>Chernoff, Y. O., Lindquist, S. L., Ono, B., Inge-Vechtomov, S. G., Liebman, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+the+chaperone+protein+Hsp104+in+propagation+of+the+yeast+prion-like+factor+%5Bpsi%2B%5D%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Role of the chaperone protein Hsp104 in propagation of the yeast prion-like factor [psi+].</a> Science. 268 (5212), 880-884 (1995).</li>
<li>Patino, M. M., Liu, J. J., Glover, J. R., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Support+for+the+prion+hypothesis+for+inheritance+of+a+phenotypic+trait+in+yeast%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Support for the prion hypothesis for inheritance of a phenotypic trait in yeast.</a> Science. 273 (5275), 622-626 (1996).</li>
<li>Wickner, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((%5BURE3%5D+as+an+altered+URE2+protein%3A+evidence+for+a+prion+analog+in+Saccharomyces+cerevisiae%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">[URE3] as an altered URE2 protein: evidence for a prion analog in Saccharomyces cerevisiae.</a> Science. 264 (5158), 566-569 (1994).</li>
<li>Sondheimer, N., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Rnq1%3A+an+epigenetic+modifier+of+protein+function+in+yeast%5BTitle%5D)+AND+%22Mol+Cell%22%5BJournal%5D)">Rnq1: an epigenetic modifier of protein function in yeast.</a> Mol Cell. 5 (1), 163-172 (2000).</li>
<li>Balbirnie, M., Grothe, R., Eisenberg, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+amyloid-forming+peptide+from+the+yeast+prion+Sup35+reveals+a+dehydrated+beta-sheet+structure+for+amyloid%5BTitle%5D)+AND+%22Proc+Natl+Acad+Sci+U+S+A%22%5BJournal%5D)">An amyloid-forming peptide from the yeast prion Sup35 reveals a dehydrated beta-sheet structure for amyloid.</a> Proc Natl Acad Sci U S A. 98 (5), 2375-2380 (2001).</li>
<li>Glover, J. R., et al. <a target="_blank" href="https://www.ncbi.nlm.nih.gov/pubmed/9182769">Self-seeded fibers formed by Sup35, the protein determinant of [PSI+], a heritable prion-like factor of S. cerevisiae.</a> Cell. 89 (5), 811-819 (1997).</li>
<li>King, C. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prion-inducing+domain+2-114+of+yeast+Sup35+protein+transforms+in+vitro+into+amyloid-like+filaments%5BTitle%5D)+AND+%22Proc+Natl+Acad+Sci+U+S+A%22%5BJournal%5D)">Prion-inducing domain 2-114 of yeast Sup35 protein transforms in vitro into amyloid-like filaments.</a> Proc Natl Acad Sci U S A. 94 (13), 6618-6622 (1997).</li>
<li>Shorter, J., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Hsp104+catalyzes+formation+and+elimination+of+self-replicating+Sup35+prion+conformers%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Hsp104 catalyzes formation and elimination of self-replicating Sup35 prion conformers.</a> Science. 304 (5678), 1793-1797 (2004).</li>
<li>Ferreira, P. C., Ness, F., Edwards, S. R., Cox, B. S., Tuite, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+elimination+of+the+yeast+%5BPSI%2B%5D+prion+by+guanidine+hydrochloride+is+the+result+of+Hsp104+inactivation%5BTitle%5D)+AND+%22Mol+Microbiol%22%5BJournal%5D)">The elimination of the yeast [PSI+] prion by guanidine hydrochloride is the result of Hsp104 inactivation.</a> Mol Microbiol. 40 (6), 1357-1369 (2001).</li>
<li>Caudron, F., Barral, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+super-assembly+of+Whi3+encodes+memory+of+deceptive+encounters+by+single+cells+during+yeast+courtship%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">A super-assembly of Whi3 encodes memory of deceptive encounters by single cells during yeast courtship.</a> Cell. 155 (6), 1244-1257 (2013).</li>
<li>Wickner, R. B., Edskes, H. K., Shewmaker, F. <a target="_blank" href="https://www.ncbi.nlm.nih.gov/pubmed/16793280">How to find a prion: [URE3], [PSI+] and [beta].</a> Methods. 39 (1), 3-8 (2006).</li>
<li>Chernoff, Y. O., Derkach, I. L., Inge-Vechtomov, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Multicopy+SUP35+gene+induces+de-novo+appearance+of+psi-like+factors+in+the+yeast+Saccharomyces+cerevisiae%5BTitle%5D)+AND+%22Curr+Genet%22%5BJournal%5D)">Multicopy SUP35 gene induces de-novo appearance of psi-like factors in the yeast Saccharomyces cerevisiae.</a> Curr Genet. 24 (3), 268-270 (1993).</li>
<li>Brown, J. C., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+heritable+switch+in+carbon+source+utilization+driven+by+an+unusual+yeast+prion%5BTitle%5D)+AND+%22Genes+Dev%22%5BJournal%5D)">A heritable switch in carbon source utilization driven by an unusual yeast prion.</a> Genes Dev. 23 (19), 2320-2332 (2009).</li>
<li>Coustou, V., Deleu, C., Saupe, S., Begueret, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+protein+product+of+the+het-s+heterokaryon+incompatibility+gene+of+the+fungus+Podospora+anserina+behaves+as+a+prion+analog%5BTitle%5D)+AND+%22Proc+Natl+Acad+Sci+U+S+A%22%5BJournal%5D)">The protein product of the het-s heterokaryon incompatibility gene of the fungus Podospora anserina behaves as a prion analog.</a> Proc Natl Acad Sci U S A. 94 (18), 9773-9778 (1997).</li>
<li>Sopko, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Mapping+pathways+and+phenotypes+by+systematic+gene+overexpression%5BTitle%5D)+AND+%22Mol+Cell%22%5BJournal%5D)">Mapping pathways and phenotypes by systematic gene overexpression.</a> Mol Cell. 21 (3), 319-330 (2006).</li>
<li>Chakrabortee, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Intrinsically+Disordered+Proteins+Drive+Emergence+and+Inheritance+of+Biological+Traits%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">Intrinsically Disordered Proteins Drive Emergence and Inheritance of Biological Traits.</a> Cell. 167 (2), 369-381 (2016).</li>
<li>Hu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Approaching+a+complete+repository+of+sequence-verified+protein-encoding+clones+for+Saccharomyces+cerevisiae%5BTitle%5D)+AND+%22Genome+Res%22%5BJournal%5D)">Approaching a complete repository of sequence-verified protein-encoding clones for Saccharomyces cerevisiae.</a> Genome Res. 17 (4), 536-543 (2007).</li>
<li>Swain, P. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Inferring+time+derivatives+including+cell+growth+rates+using+Gaussian+processes%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">Inferring time derivatives including cell growth rates using Gaussian processes.</a> Nat Commun. 7, 13766(2016).</li>
<li>Jarosz, D. F., Lancaster, A. K., Brown, J. C., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+evolutionarily+conserved+prion-like+element+converts+wild+fungi+from+metabolic+specialists+to+generalists%5BTitle%5D)+AND+%22Cell%22%5BJournal%5D)">An evolutionarily conserved prion-like element converts wild fungi from metabolic specialists to generalists.</a> Cell. 158 (5), 1072-1082 (2014).</li>
<li>Neiman, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sporulation+in+the+budding+yeast+Saccharomyces+cerevisiae%5BTitle%5D)+AND+%22Genetics%22%5BJournal%5D)">Sporulation in the budding yeast Saccharomyces cerevisiae.</a> Genetics. 189 (3), 737-765 (2011).</li>
<li>Gietz, D., St Jean, A., Woods, R. A., Schiestl, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Improved+method+for+high+efficiency+transformation+of+intact+yeast+cells%5BTitle%5D)+AND+%22Nucleic+Acids+Res%22%5BJournal%5D)">Improved method for high efficiency transformation of intact yeast cells.</a> Nucleic Acids Res. 20 (6), 1425(1992).</li>
<li>Formosa, T., Nittis, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Suppressors+of+the+temperature+sensitivity+of+DNA+polymerase+alpha+mutations+in+Saccharomyces+cerevisiae%5BTitle%5D)+AND+%22Mol+Gen+Genet%22%5BJournal%5D)">Suppressors of the temperature sensitivity of DNA polymerase alpha mutations in Saccharomyces cerevisiae.</a> Mol Gen Genet. 257 (4), 461-468 (1998).</li>
<li>Christiano, R., Nagaraj, N., Frohlich, F., Walther, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Global+proteome+turnover+analyses+of+the+Yeasts+S.+cerevisiae+and+S.+pombe%5BTitle%5D)+AND+%22Cell+Rep%22%5BJournal%5D)">Global proteome turnover analyses of the Yeasts S. cerevisiae and S. pombe.</a> Cell Rep. 9 (5), 1959-1965 (2014).</li>
<li>Lancaster, A. K., Nutter-Upham, A., Lindquist, S., King, O. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((PLAAC%3A+a+web+and+command-line+application+to+identify+proteins+with+prion-like+amino+acid+composition%5BTitle%5D)+AND+%22Bioinformatics%22%5BJournal%5D)">PLAAC: a web and command-line application to identify proteins with prion-like amino acid composition.</a> Bioinformatics. 30 (17), 2501-2502 (2014).</li>
<li>Halfmann, R., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Screening+for+amyloid+aggregation+by+Semi-Denaturing+Detergent-Agarose+Gel+Electrophoresis%5BTitle%5D)+AND+%22J+Vis+Exp%22%5BJournal%5D)">Screening for amyloid aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis.</a> J Vis Exp. (17), (2008).</li>
<li>Rogoza, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Non-Mendelian+determinant+%5BISP%2B%5D+in+yeast+is+a+nuclear-residing+prion+form+of+the+global+transcriptional+regulator+Sfp1%5BTitle%5D)+AND+%22Proc+Natl+Acad+Sci+U+S+A%22%5BJournal%5D)">Non-Mendelian determinant [ISP+] in yeast is a nuclear-residing prion form of the global transcriptional regulator Sfp1.</a> Proc Natl Acad Sci U S A. 107 (23), 10573-10577 (2010).</li>
<li>Shorter, J., Lindquist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prions+as+adaptive+conduits+of+memory+and+inheritance%5BTitle%5D)+AND+%22Nat+Rev+Genet%22%5BJournal%5D)">Prions as adaptive conduits of memory and inheritance.</a> Nat Rev Genet. 6 (6), 435-450 (2005).</li>
<li>Tanaka, M., Chien, P., Naber, N., Cooke, R., Weissman, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Conformational+variations+in+an+infectious+protein+determine+prion+strain+differences%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Conformational variations in an infectious protein determine prion strain differences.</a> Nature. 428 (6980), 323-328 (2004).</li>
<li>Tanaka, M., Weissman, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+efficient+protein+transformation+protocol+for+introducing+prions+into+yeast%5BTitle%5D)+AND+%22Methods+Enzymol%22%5BJournal%5D)">An efficient protein transformation protocol for introducing prions into yeast.</a> Methods Enzymol. 412, 185-200 (2006).</li>
<li>Roberts, B. T., Wickner, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Heritable+activity%3A+a+prion+that+propagates+by+covalent+autoactivation%5BTitle%5D)+AND+%22Genes+Dev%22%5BJournal%5D)">Heritable activity: a prion that propagates by covalent autoactivation.</a> Genes Dev. 17 (17), 2083-2087 (2003).</li>
<li>Ozbudak, E. M., Thattai, M., Lim, H. N., Shraiman, B. I., Van Oudenaarden, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Multistability+in+the+lactose+utilization+network+of+Escherichia+coli%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Multistability in the lactose utilization network of Escherichia coli.</a> Nature. 427 (6976), 737-740 (2004).</li>
</ol>

The authors have nothing to disclose.

The first yeast prions were identified by their unusual phenotypes and perplexing patterns of inheritance. The characteristics of these prions were then used to build algorithms and computational tools to screen for additional prion proteins. The method described here, in contrast, is experimental and relies on transient overexpression to create a lasting change-a stable state-encoded in protein conformation. However, if the efficiency of &#34;seeding&#34; prion assembly by overexpression for any given protein is very lo...

Biological systems frequently experience transient fluctuations in protein abundance. Whether these have a lasting impact in shaping the phenotype of an organism or of future generations remains unclear. The best-known instances of this biology involve a rare class of proteins, prions, which drive the emergence of heritable traits without genome modification. Instead, these proteinaceous and infectious particles transmit phenotypes via self-perpetuating changes to protein conformation1,2. This type of inheritance was discovered as the cause of the unusual inheritance patterns of a devastating neurodegenerative disease. However, studies in organisms ranging from fungi to mammals3,4,5,6,7,8,9,10 have since revealed that prion-like elements can confer adaptive value. Nonetheless, prions have been viewed as a fascinating but rare biological oddity.
This prevailing wisdom is in part held because the characterization of protein-based inheritance has long been restricted by a small set of examples. Recent systematic screening efforts have widened this picture significantly by identifying several new bona fide prions11 and almost two dozen protein domains12 with the capacity to fuel prion-like conformational conversion. However, because these approaches have generally focused on strong amino acid sequence biases, the prions that have been discovered share the biochemical properties of the founding yeast prions [PSI+]13,14, [URE3]15, and [RNQ+]11,16. These include: 1) modular domains that are rich in long polymeric stretches of asparagine (N) and glutamine (Q), 2) assembly into an amyloid [PRION+] conformation17,18,19, and 3) complete reliance on disaggregase Hsp104 function for faithful propagation from mother to daughter13,20,21. Indeed, many bona fide prions, including [GAR+], [Het-s], and even the original prion (PrPSc), would be missed under such stringent criteria. Perhaps more importantly, they would be unable to capture any novel mechanisms of protein-based inheritance22. Thus, the true biological breadth of such phenomena may be far more common in nature than previously assumed.
To investigate this question, a high-throughput, proteome-wide strategy was employed. A hallmark of all prions, including PrPSc, [GAR+], and [Het-s], is that the transient overexpression of the causal proteins strongly increases the rate of prion acquisition15,23,24,25,26. We took advantage of this feature to systematically ask, across the entire yeast ORFeome, if stable protein-based, epigenetic states could be initiated by transiently inducing the overexpression of individual proteins. It is well known that protein overexpression can alter phenotypes27. However, prion proteins are unusual because their temporary overproduction produces a change in phenotype that is heritable for many hundreds of generations after the initial overexpression. We previously took advantage of this feature, as well as the unusual inheritance patterns of protein-based genetic elements, to identify dozens of proteins that are capable of heritably re-wiring phenotypic landscapes without altering the genome28. Although some identified proteins were previously known as prions, most were not, underscoring the power of this approach to uncover new forms of protein-based inheritance.

<table><tbody><tr><td>Guanidine hydrochloride</td><td>Sigma</td><td>Cat#G3272-25G</td><td>Chemical</td></tr><tr><td>Manganese chloride</td><td>Sigma</td><td>Cat#M8054-100G</td><td>Chemical</td></tr><tr><td>Ethidium bromide</td><td>Sigma</td><td>E1510</td><td>Chemical</td></tr><tr><td>5-Fluoroorotic Acid</td><td>Sigma</td><td>Cat#F5013-50MG</td><td>Chemical</td></tr><tr><td>BY4741 &lt;em&gt;MATa (his3&amp;Delta;1 leu2&amp;Delta;0 LYS2 met15&amp;Delta;0 ura3&amp;Delta;0)&lt;/em&gt;</td><td>Winston et al., 1995; Brachmann et al., 1998</td><td>N/A</td><td>Yeast strain</td></tr><tr><td>BY4741 &lt;em&gt;MAT&amp;alpha; (his3&amp;Delta;1 leu2&amp;Delta;0 lys2&amp;Delta;0 MET15 ura3&amp;Delta;0)&lt;/em&gt;</td><td>Winston et al., 1995; Brachmann et al., 1998</td><td>N/A</td><td>Yeast strain</td></tr><tr><td>Hsp70 (K69M)&amp;nbsp;</td><td>Jarosz et al., 2014b</td><td>N/A</td><td>Plasmid</td></tr><tr><td>FLEXGene library</td><td>Hu et al., 2007</td><td>N/A</td><td>Plasmid library</td></tr><tr><td>Dextrose (glucose)</td><td>Fisher Scientific</td><td>D16-3</td><td>Media component</td></tr><tr><td>Raffinose</td><td>Sigma</td><td>R0250-25G</td><td>Media component</td></tr><tr><td>Galactose</td><td>Fisher Scientific</td><td>BP656-500</td><td>Media component</td></tr><tr><td>CSM</td><td>Sunrise Science</td><td>1001-100</td><td>Media component</td></tr><tr><td>CSM-URA</td><td>Sunrise Science</td><td>1004-100</td><td>Media component</td></tr><tr><td>CSM-LYS</td><td>Sunrise Science</td><td>1032-100</td><td>Media component</td></tr><tr><td>CSM-MET</td><td>Sunrise Science</td><td>1019-100</td><td>Media component</td></tr><tr><td>CSM-LYS-MET</td><td>Sunrise Science</td><td>1035-100</td><td>Media component</td></tr><tr><td>yeast extract</td><td>Fisher Scientific</td><td>BP1422-2</td><td>Media component</td></tr><tr><td>peptone</td><td>Research Products International</td><td>P20240-5000</td><td>Media component</td></tr><tr><td>bacto-peptone</td><td>BD</td><td>211677</td><td>Media component</td></tr><tr><td>glycerol</td><td>EMD Millipore</td><td>GX0185-2</td><td>Media component</td></tr><tr><td>yeast nitrogen base w/o amino acids</td><td>BD</td><td>291920</td><td>Media component</td></tr><tr><td>agar</td><td>IBI Scientific</td><td>IB49172</td><td>Media component</td></tr><tr><td>Adenine sulfate</td><td>Sigma</td><td>A3159-25G</td><td>Media component</td></tr><tr><td>Potassium acetate</td><td>Sigma</td><td>P1190-500G</td><td>Media component</td></tr><tr><td>Uracil</td><td>Sigma</td><td>U0750-100G</td><td>Media component</td></tr><tr><td>Histidine</td><td>Sigma</td><td>H8000-100G</td><td>Media component</td></tr><tr><td>Leucine</td><td>Sigma</td><td>L8000-25G</td><td>Media component</td></tr><tr><td>Lysine</td><td>Sigma</td><td>L5501-25G</td><td>Media component</td></tr><tr><td>RNase I&amp;nbsp;</td><td>Thermo Fisher Scientific</td><td>EN0601</td><td>Enzyme</td></tr><tr><td>biotinylated DNase</td><td>Thermo Fisher Scientific</td><td>AM1906</td><td>Enzyme</td></tr><tr><td>zymolyase 100T (yeast lytic enzyme)</td><td>Sunrise Science</td><td>N0766555</td><td>Enzyme</td></tr><tr><td>Microplate reader</td><td>BioTek</td><td>Synergy H1</td><td>Equipment</td></tr><tr><td>Microplate stacker</td><td>BioTek</td><td>BioStack3</td><td>Equipment</td></tr><tr><td>Plate filler</td><td>BiotTek</td><td>EL406</td><td>Equipment</td></tr><tr><td>Liquid handling robot</td><td>Beckman Coulter</td><td>Biomek FX</td><td>Equipment</td></tr></tbody></table>

high-throughput screening for protein-based inheritance in s. cerevisiae

High-throughput Screening for Protein-based Inheritance in S. cerevisiae

The encoding of biological information that is accessible to future generations is generally achieved via changes to the DNA sequence. Long-lived inheritance encoded in protein conformation (rather than sequence) has long been viewed as paradigm-shifting but rare. The best characterized examples of such epigenetic elements are prions, which possess a self-assembling behavior that can drive the heritable manifestation of new phenotypes. Many archetypal prions display a striking N/Q-rich sequence bias and assemble into an amyloid fold. These unusual features have informed most screening efforts to identify new prion proteins. However, at least three known prions (including the founding prion, PrPSc) do not harbor these biochemical characteristics. We therefore developed an alternative method to probe the scope of protein-based inheritance based on a property of mass action: the transient overexpression of prion proteins increases the frequency at which they acquire a self-templating conformation. This paper describes a method for analyzing the capacity of the yeast ORFeome to elicit protein-based inheritance. Using this strategy, we previously found that &gt;1% of yeast proteins could fuel the emergence of biological traits that were long-lived, stable, and arose more frequently than genetic mutation. This approach can be employed in high throughput across entire ORFeomes or as a targeted screening paradigm for specific genetic networks or environmental stimuli. Just as forward genetic screens define numerous developmental and signaling pathways, these techniques provide a methodology to investigate the influence of protein-based inheritance in biological processes.

Protein overexpression is known to dramatically alter cellular phenotypes27. Indeed, with an initial screening approach, hundreds of new phenotypes were reproducibly recovered from the overexpression of clones from the yeast ORFeome using just ten stressors. However, the assays described above allow for the assessment of whether cells retain any long-term stable phenotypes following this overexpression. One protein capable of encoding such a state is Psp1. Psp1 is ...

This protocol describes a high-throughput methodology to functionally screen for protein-based inheritance in S. cerevisiae.

The encoding of biological information that is accessible to future generations is generally achieved via changes to the DNA sequence. Long-lived ...

The overall goal of this high-throughput yeast phenotyping is to screen for proteins that illicit a lasting phenotypic memory of passed over expression, as a proxy for protein-based inheritance. This method can help answer key questions in the yeast Prion field, such as, how many proteins can it illicit inheritance of this type. The main advantage of this technique is that you can screen many proteins and pathways in an unbiased fashion.Start this procedure by growing the appropriate yeast cells in a 96 well plate at 30 degrees celsius, as described in the text protocol. Visually inspect the cultures to confirm that the cultures are saturated, cells should be visible by eye, at the bottom of each well. Use a liquid handling robot to prepare 384 well plates, containing 45 microliters of the appropriate medium per well.First, dispense Scal-URA into the wells of a 384 well plate. Then dispense Scal-URA plus the stressor of interest into the wells of a second plate, 20 millimolar of manganese chloride is used as the stressor in this experiment. Thirdly, dispense SD-URA, which will not induce plasmid expression, plus manganese chloride into another plate.Lower the 96 well plate containing the cultures onto the liquid handling robot and inoculate a one to four array of one microliter from each well of the 96 well plate, into four separate wells of each 384 well plate filled with a different media. Immediately place the plates with cells on a microplate stacker at room temperature and atmospheric carbon dioxide. Set the protocol for a 72 hour continuous loop, measuring the optical density at 600 nanometers with the microplate reader.After the growth measurements, transfer one microliter per well of the SCal-URA induced cultures that experienced protein over-expression to new 384 well plates, containing 45 microliters per well of ST-URA medium that does not permit protein expression of the plasmid. In parallel, perform analogous inoculations of a second set of 384 well plate containing 45 microliters per well of ST-URA from the cultures that were grown in ST-URA in the presence of the stressor. Place the plates in a humidified chamber and grow the plates for 48 hours at 30 degree celsius to saturation.After 48 hours, use the plates to re-inoculate one microliter per well in 384 well plates containing 45 microliters per well of ST-URA. Then, perform a separate re-inoculation of one microliter per well from the same source plate into a separate 384 well plate containing 45 microliters per well of ST-URA with the stressor. Immediately place the plates with cells of the microstacker at room temperature and atmospheric carbon dioxide and set the protocol for a 48 hour continuous loop, measuring the optical density at 600 nanometers with a microplate reader.When the growth measurements are complete, use the plate reader software to export the time versus optical density at 600 nanometer measurements as an XY table. Group columns of the optical density measurements for each biological replicate together and calculate the mean. Create an XY plot of time versus optical density at 600 nanometers to generate growth curves.For cultures that chose significant growth differences in response to a given stressor, dependent upon ancestral protein over-expression, take one microliter from each biological replicate, dilute in 10 milliliters of water and then plate 50 microliters on plates containing 5-FOA. Grow at 30 degree celsius for three days. If this results in too many or too few colonies per plate, adjust the dilution factor accordingly.100 to 200 colonies per plate is ideal. Pick eight to 32 single colonies with autoclave toothpicks and pin them to 96 well plates containing 150 microliters of SDCSM per well. Place the plates in a humidified chamber and grow to saturation for 48 to 72 hours at 30 degrees celsius.Use these cultures to inoculate two new sets of 96 well plates containing 150 microliters per well of SDCSM, both with and without the stressor. Place the plates on a microplate stacker and set the protocol to measure the optical density at 600 nanometers on a 48 hour continuous loop. After 48 hours, analyze the data as shown earlier and confirm that the significant growth differences seen earlier, are maintained after plasmid loss.The cells that maintain the induced phenotypes are then tested for classic hallmarks of protein-based inheritance as described in the text protocol. This protein-based inheritance screen revealed the transient over-expression of the PSP1 open reading frame, drives a resistance to manganese chloride that was maintained for hundreds of generations in cells, long after over-expression had ceased. Prion predicting algorithms scored the end terminus of PSP1 as moderately Prion-like.In contrast, the algorithms predicted virtually no significant Prion-like sequence features from most inducing proteins recovered on the screen, as shown by this representative analysis. Growth measurements of strains and SDCSM with manganese chloride, normalized to a corresponding naive PSP1 minus control, indicated that inhibition of the HSP104 disaggregase does not impair PSP1 dependent manganese chloride resistance whereas the removal of the HSP70 chaperone and the PSP1 gene, heritably eliminates this phenotype. All spores from single tetrads of crosses between strains, harboring the PSP1 dependent phenotypic state and naive strains, display manganese chloride resistance, indicating non-mendelian inheritance of the phenotype.A comparison of the infectivity for protein transformation between mock lysates and PSP1 harboring lysates as the transmissible material, showed that over 53%of naive cells transformed with seeded PSP1, received the corresponding manganese chloride resistance phenotype. Once mastered, this technique can be done in a couple of weeks, including incubation steps and the preparation of most screening steps can be done in less than two hours per day, even with a large number of plates. While attempting this procedure, it is important to remember to plan exactly what you wanna test beforehand and keep in mind the scale of the experiment.Now this is especially important to beginners of the technique. Following this procedure, other methods like those described in the text protocol can be performed to determine if the phenotypes observed in the screening display a true, Prion-like pattern of inheritance. After its development, this technique paved the way for researchers in the field of epigenetics to explore the breadth of Prion biology in sacralis service CI.After watching this video, you should have a good understanding of how to design a high throughput screen for new forms of protein-based inheritance in yeast, in both an unbiased and targeted fashion.Don't forget, that certain chemical stressors such as DNA damaging agents can be extremely hazardous and precautions, such as wearing personal protective equipment, should always be taken while performing this procedure.

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Research

JoVE Journal

Biology

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A high-throughput method to globally study the organelle morphology in S. cerevisiae

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High-throughput Yeast Plasmid Overexpression Screen

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Directed Evolution Method in Saccharomyces cerevisiae: Mutant Library Creation and Screening

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Mating-based Overexpression Library Screening in Yeast

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High Throughput Yeast Strain Phenotyping with Droplet-Based RNA Sequencing

This work describes a protocol for a multicopy suppressor genetic screen in Schizosaccharomyces pombe. This screen uses a genome-wide plasmid library to identify suppressor clone(s) of a loss-of-function phenotype associated with a query mutant strain. Novel genetic suppressors of the ell1 null mutant were identified using this screen.

Genetic Screen for Identification of Multicopy Suppressors in Schizosaccharomyces pombe

This protocol describes the essential steps for conducting yeast surface display selection campaigns to enrich protein variants binding to an antigen of interest.

Protein Engineering by Yeast Surface Display

Learn high-throughput screening for protein-based inheritance in S. cerevisiae using unbiased phenotypic memory assays. This method enables researchers to identify prion-like proteins and study epigenetic mechanisms in yeast.

High-throughput Screening for Protein-based Inheritance in S. cerevisiae

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