Name: protein regulation by covalent bonds
Uploaded: 2023-04-30T18:28:43.000Z
Duration: 2 min 4 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-1

Covalently Linked Protein Regulators

Beaucoup de protéines sont régulées par des molécules liées par covalence y compris des groupes fonctionnels, comme les groupements méthyle ou acétyles et des petites protéines, telles que l'ubiquitine. Des liaisons covalentes se produisent sur des acides aminés spécifiques dans la chaîne polypeptidique. Par exemple, les groupes phosphate sont liés de façon covalente à la sérine, à la thréonine ou à la tyrosine.Les groupes méthyle et acétyle sont liés à la lysine. Et l'ubiquitine est liée aux résidus de lysine, cystine, sérine ou thréonine. Une enzyme ou une paire d'enzymes catalyse réversiblement ces modifications post-traductionnelles.Et l'acétyltransférase peut acétyler une protéine alors qu'une désacétylase peut, plus tard enlever le groupe. Ces modifications peuvent changer la fonction ou la localisation d'une protéine dans une cellule. Par exemple, l'acétylation des protéines histones régule l'expression génique en ouvrant la structure de l'ADN pour activer la transcription des gènes.La méthylation des protéines histones, par contre, est connue pour réprimer la transcription en resserrant la structure. Un autre exemple est p53, une protéine multi-fonctionnelle suppresseur de tumeur qui subit plusieurs modifications covalentes en réponse au stress. L'exposition à des agents nuisibles à l'ADN, tels que les rayons UV et gamma peut entraîner une phosphorylation de la protéine.La phosphorylation améliore la stabilité et active p53, ce qui le lie à l'ADN endommagé par le rayonnement et empêche les cellules avec l'ADN muté de se diviser de manière incontrôlable. En plus de la phosphorylation, différents types de modifications survenant sur une seule molécule de protéine, comme p53, lui permettent de contrôler précisément ses fonctions, telles que l'arrêt du cycle cellulaire, la réparation de l'ADN et l'apoptose de la cellule.

<ol>
	<li>1ID PDB : 1UBQ 
	Vijay-Kumar, S., Bugg, C.E., Cook, W.J. (1987) Structure de l’ubiquitine affinée à une résolution de 1,8 A. J Mol Biol 194 : 531 à 544. DOI : 10.1016/0022-2836(87)90679-6</li>
	<li>H.M. Berman, J. Westbrook, Z. Feng, G. Gilliland, T.N. Bhat, H. Weissig, I.N. Shindyalov, P.E. Bourne. (2000) La banque de données sur les protéines Recherche sur les acides nucléiques, 28 : 235-242.</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol* : Vers une bibliothèque et des outils communs pour les graphiques moléculaires web MolVA/EuroVis Proceedings. doi :10.2312/molva.20181103</li>
	<li>Alberts et al., 6e édition ; pages 157-158, 165-166</li>
	<li>Le, D. D. et Fujimori, D. G. (2012). Enzymes méthylantes des protéines et des acides nucléiques : mécanismes et régulation. Opinion actuelle en biologie chimique, 16(5-6), 507-515. doi :10.1016/j.cbpa.2012.09.014</li>
	<li>Khidekel, N. et Hsieh-Wilson, L. C. (2004). Un « standard moléculaire » : les modifications covalentes des protéines et leur impact sur la transcription. Chimie organique et biomoléculaire, 2(1), 1-7.</li>
	<li>Maclaine, N. J. et Hupp, T. R. (2009). La régulation de p53 par phosphorylation : un modèle de la façon dont des signaux distincts s’intègrent dans la voie p53. Vieillissement, 1(5), 490.</li>
</ol>

régulateurs protéiques liés de façon covalente

Les protéines peuvent subir de nombreux types de modifications post-traductionnelles, souvent en réponse à des changements dans leur environnement. Ces modifications jouent un rôle important dans la fonction et la stabilité de ces protéines. Les molécules liées de manière covalente comprennent des groupes fonctionnels, tels que les groupes méthyle, acétyle et phosphate, ainsi que de petites protéines, telles que l'ubiquitine. Il existe environ 200 types différents de régulateurs covalents identifiés.

Ces groupes modifient des acides aminés spécifiques dans une protéine. Les groupes phosphate ne peuvent être liés de manière covalente qu'aux acides aminés sérine, thréonine et tyrosine, tandis que les groupes méthyle et acétyle ne peuvent être liés qu'à la lysine. Ces groupes sont ajoutés et supprimés d’une protéine par une enzyme ou une paire d’enzymes. Par exemple, une acétyltransférase ajoute un groupe acétyle à une protéine et une désacétylase peut le supprimer. Chacun de ces modificateurs peut avoir des effets différents sur la protéine à laquelle il est attaché en fonction du nombre et de la localisation des modifications. Lorsqu'une seule molécule d'ubiquitine est liée de manière covalente à un certain récepteur de surface cellulaire, cette protéine est ciblée pour l'endocytose ; d’autre part, lorsque plusieurs ubiquitines liées entre elles sont attachées à cette protéine, elle est marquée comme cible de dégradation protéolytique.

Une seule protéine peut subir plusieurs modifications simultanément pour contrôler sa fonction. Un exemple bien connu de protéine régulée par de multiples modifications covalentes est la protéine suppresseur de tumeur, p53. La p53 subit diverses modifications en réponse à divers types de stress, notamment les radiations et les agents cancérigènes. Certaines modifications incluent la phosphorylation, l'acétylation et la sumoylation en réponse aux rayonnements UV et gamma. Les sites et les types de modifications peuvent varier en fonction du facteur de stress. Des études ont montré que les rayons UV et gamma peuvent entraîner la phosphorylation de la sérine 33, mais que la sérine 392 peut être phosphorylée lorsqu'elle est exposée aux rayons UV, mais pas aux rayons gamma. D'autres types de stress, tels que l'exposition à l'hypoxie, aux antimétabolites et à l'actinomycine D, peuvent entraîner l'acétylation de la p53. Les modifications peuvent également varier selon les différents types de cellules et organismes.

Régulateurs protéiques liés de façon covalente

Les protéines peuvent subir de nombreux types de modifications post-traductionnelles, souvent en réponse à des changements dans leur environnement. Ces modifications jouent un rôle ...

Education

Enseignement

JoVE Core

Cell Biology

Biologie cellulaire

Unit 1

Unité 1

Protein Function

Fonction des protéines

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

protein regulation by covalent bonds

Protein regulation by covalent bonds helps control how cells respond to changing conditions. A covalent bond is a strong chemical link, and in this context it can change how a protein behaves.

Some regulators work by attaching a chemical group directly to a protein. This covalent change can alter the protein's activity, its location in the cell, or how long it stays active. Because the change is built into the protein itself, it can have a strong effect on cell function.

Covalently linked protein regulators are an important part of cell control and signaling. They help cells turn protein functions on or off at the right time. This type of regulation is a key idea in molecular biology and protein function.

Protein Regulation by Covalent Bonds

ligand binding sites

Ligand Binding Sites in Proteins

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protein-protein interfaces

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conserved binding sites

Conserved Binding Sites in Protein Families

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cofactors and coenzymes

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cooperative allosteric transitions

Allosteric Changes in Protein Shape

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protein kinases and phosphatases

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gtpases and their regulation

GTPase Molecular Switches and Control

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covalently linked protein regulators

Protein regulation by covalent bonds helps control how cells respond to changing conditions. A covalent bond is a strong chemical link, and in this context it can change how a protein behaves. Some regulators work by attaching a chemical group directly to a protein. This covalent change can alter the protein's activity, its location in the cell, or how long it stays active. Because the change is built into the protein itself, it can have a strong effect on cell function. Covalently linked...

protein complexes with interchangeable parts

protein-complexes-with-interchangeable-parts

Modular Protein Complexes in Cells

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mechanical protein function

Proteins That Generate Cell Movement

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structural protein function

Structural Proteins in Cells and Tissues

Structural proteins help cells and tissues keep their shape and strength. They are an important part of living systems because they provide support where it is needed most. Many structural proteins form fibers or other sturdy forms that resist stretching and wear. These proteins work as building materials in the body and help keep structures stable over time. Examples of structural proteins include collagen, actin, myosin, and keratin. Each one supports a different part of the body, but all...

protein networks

Mapping Protein Interaction Networks

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key terms and concepts

Learn how covalent bonds can regulate proteins by changing activity, location, and stability. A clear K12 summary of protein control in cells.

Protein Regulation by Covalent Bonds | JoVE K12

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HS-LS1-2

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HS-LS1-3

Protein Regulation by Covalent Bonds

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