A Central Cysteine Residue Is Essential for the Thermal Stability and Function of SUMO-1 Protein and SUMO-1 Peptide–Protein Conjugates

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• 作者：Hervé Drobecq ; Emmanuelle Boll ; Magalie Sénéchal ; Rémi Desmet ; Jean-Michel Saliou ; Jean-Jacques Lacapère ; Alexandra Mougel ; Jérôme Vicogne ; Oleg Melnyk
• 刊名：Bioconjugate Chemistry
• 出版年：2016
• 出版时间：June 15, 2016
• 年：2016
• 卷：27
• 期：6
• 页码：1540-1546
• 全文大小：498K
• 年卷期：0
• ISSN：1520-4812

文摘

SUMOylation constitutes a major post-translational modification (PTM) used by the eukaryote cellular machinery to modulate protein interactions of the targeted proteins. The small ubiquitin-like modifier-1 (SUMO-1) features a central and conserved cysteine residue (Cys52) that is located in the hydrophobic core of the protein and in tight contact with Phe65, suggesting the occurrence of an S/π interaction. To investigate the importance of Cys52 on SUMO-1 thermal stability and biochemical properties, we produced by total chemical synthesis SUMO-1 or SUMO-1 Cys52Ala peptide–protein conjugates featuring a native isopeptidic bond between SUMO-1 and a peptide derived from p53 tumor suppressor protein. The Cys52Ala modification perturbed SUMO-1 secondary structure and resulted in a dramatic loss of protein thermal stability. Moreover, the cleavage of the isopeptidic bond by the deconjugating enzyme Upl1 was significantly less efficient than for the wild-type conjugate. Similarly, the in vitro SUMOylation of RanGap1 by E1/E2 conjugating enzymes was significantly less efficient with the SUMO-1 C52A analog compared to wild-type SUMO-1. These data demonstrate the critical role of Cys52 in maintaining SUMO-1 conformation and function and the importance of keeping this cysteine intact for the study of SUMO-1 protein conjugates.