in-vitro-reconstitution-light-harvesting-complexes-plants-green

<em>In Vitro</em> Reconstitution of Light-harvesting Complexes of Plants and Green Algae

In plants and green algae, light is captured by the light-harvesting complexes (LHCs), a family of integral membrane proteins that coordinate chlorophylls ...

VU University Amsterdam

The Maize Gene Discovery Project (MGDP) is a 5-year NSF-funded plant genome initiative that began in 1998. The MGDP collaboration involves researchers at six universities from diverse disciplines with the common goal of discovering new maize genes and developing tools for the phenotypic characterization of maize mutants. The project utilizes several approaches: EST sequencing, cDNA microarray production, and the discovery of gene function and genomic sequence through the use of a recombinant Mu1 transposon ( RescueMu). Current achievements of the MGDP (NSF 98-72657) include the sequencing of over 120,000 maize ESTs from diverse cDNA libraries, and over 70,000 RescueMu flanking sequences, as well as the cataloguing of mutant seed and cob phenotypes of 23,000 maize ears, 6,200 families of maize seedlings, and 4,000 families of adult maize plants carrying MuDR/Mu and RescueMu insertion alleles. A consolidation of over 24,000 unique sequences from 19 libraries has been made into the first two of the planned set of four "Unigene" microarray slides. In addition, slides for four EST libraries have been produced. These microarray slides, EST clones, library plates of immortalized RescueMu bacterial cultures, and seed are all available online (http://www.zmdb.iastate.edu). The ZmDB website posts periodic assemblies of all maize EST and genomic sequences available from GenBank. ZmDB is also a portal for sequence analysis software designed to aid in gene discovery: MuSeqBox, GeneSeqer, and SplicePredictor. In addition, ZmDB contains links to other plant and genetics websites.

Progress in maize gene discovery: a project update.

In mammalian cells, the repair of DNA bases that have been damaged by reactive oxygen species is primarily initiated by a series of DNA glycosylases that include OGG1, NTH1, NEIL1, and NEIL2. To explore the functional significance of NEIL1, we recently reported that neil1 knock-out and heterozygotic mice develop the majority of symptoms of metabolic syndrome (Vartanian, V., Lowell, B., Minko, I. G., Wood, T. G., Ceci, J. D., George, S., Ballinger, S. W., Corless, C. L., McCullough, A. K., and Lloyd, R. S. (2006) Proc. Natl. Acad. Sci. U. S. A. 103, 1864-1869). To determine whether this phenotype could be causally related to human disease susceptibility, we have characterized four polymorphic variants of human NEIL1. Although three of the variants (S82C, G83D, and D252N) retained near wild type levels of nicking activity on abasic (AP) site-containing DNA, G83D did not catalyze the wild type beta,delta-elimination reaction but primarily yielded the beta-elimination product. The AP nicking activity of the C136R variant was significantly reduced. Glycosylase nicking activities were measured on both thymine glycol-containing oligonucleotides and gamma-irradiated genomic DNA using gas chromatography/mass spectrometry. Two of the polymorphic variants (S82C and D252N) showed near wild type enzyme specificity and kinetics, whereas G83D was devoid of glycosylase activity. Although insufficient quantities of C136R could be obtained to carry out gas chromatography/mass spectrometry analyses, this variant was also devoid of the ability to incise thymine glycol-containing oligonucleotide, suggesting that it may also be glycosylase-deficient. Extrapolation of these data suggests that individuals who are heterozygous for these inactive variant neil1 alleles may be at increased risk for metabolic syndrome.

Human polymorphic variants of the NEIL1 DNA glycosylase.

Feedback mechanisms that dissipate excess photoexcitations in light-harvesting complexes (LHCs) are necessary to avoid detrimental oxidative stress in most photosynthetic eukaryotes. Here we demonstrate the unique ability of LHCSR, a stress-related LHC from the model organism Chlamydomonas reinhardtii, to sense pH variations, reversibly tuning its conformation from a light-harvesting state to a dissipative one. This conformational change is induced exclusively by the acidification of the environment, and the magnitude of quenching is correlated to the degree of acidification of the environment. We show that this ability to respond to different pH values is missing in the related major LHCII, despite high structural homology. Via mutagenesis and spectroscopic characterization, we show that LHCSR's uniqueness relies on its peculiar C-terminus subdomain, which acts as a sensor of the lumenal pH, able to tune the quenching level of the complex.

Article	Year
Progress in maize gene discovery: a project update. Functional & integrative genomics\| PubMed ID: 12590340	2003
Human polymorphic variants of the NEIL1 DNA glycosylase. The Journal of biological chemistry\| PubMed ID: 17389588	2007
Regulation of light harvesting in the green alga Chlamydomonas reinhardtii: the C-terminus of LHCSR is the knob of a dimmer switch. Journal of the American Chemical Society\| PubMed ID: 24261574	2013

Laura M. Roy

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