Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
J Mol Biol. 2010 Jan 29;395(4):844-59. doi: 10.1016/j.jmb.2009.10.042. Epub 2009 Oct 23.
S-Nitrosylation, the selective and reversible addition of nitric oxide (NO) moiety to cysteine (Cys) sulfur in proteins, regulates numerous cellular processes. In recent years, proteomic approaches that are capable of identifying nitrosylated Cys residues have been developed. However, the features underlying the specificity of Cys modification with NO remain poorly defined. Previous studies suggested that S-nitrosylated Cys may be flanked by an acid-base motif or hydrophobic areas and show high reactivity, low pK(a), and high sulfur atom exposure. In the current study, we prepared an extensive, manually curated data set of proteins with S-nitrosothiols, accounting for a variety of biochemical functions, organisms of origin, and physiological responses to NO. Analysis of this generic NO-Cys data set revealed that proximal acid-base motif, Cys pK(a), sulfur atom exposure, and Cys conservation or hydrophobicity in the vicinity of the modified Cys do not define the specificity of S-nitrosylation. Instead, this analysis revealed a revised acid-base motif, which is located more distantly to the Cys and has its charged groups exposed. We hypothesize that, rather than being strictly used for direct activation of Cys, the modified acid-base motif is engaged in protein-protein interactions thereby contributing to trans-nitrosylation as an important and widespread mechanism for reversible modification of Cys with NO moiety. For proteins lacking the revised motif, we discuss alternative mechanisms including a potential role of nitrosoglutathione as a trans-acting agent.
S-亚硝基化作用，即一氧化氮（NO）部分选择性可逆地添加到蛋白质中半胱氨酸（Cys）的硫原子上，调节着众多细胞过程。近年来，已经开发出能够鉴定亚硝基化 Cys 残基的蛋白质组学方法。然而，NO 对 Cys 修饰特异性的特征仍未得到明确界定。先前的研究表明，S-亚硝基化的 Cys 可能被酸碱基序或疏水区包围，并表现出高反应性、低 pK(a)和高硫原子暴露度。在本研究中，我们制备了一个广泛的、手动整理的含 S-亚硝硫醇蛋白质数据集，涵盖了各种生化功能、起源生物和对 NO 的生理反应。对这个通用的 NO-Cys 数据集的分析表明，邻近的酸碱基序、Cys pK(a)、硫原子暴露度以及修饰 Cys 附近的 Cys 保守性或疏水性并不能定义 S-亚硝化的特异性。相反，这种分析揭示了一个经过修订的酸碱基序，它位于更远的位置，并且其带电基团暴露在外。我们假设，修饰后的酸碱基序不是严格用于直接激活 Cys，而是参与蛋白质-蛋白质相互作用，从而作为一种重要且广泛的机制，通过 NO 部分可逆修饰 Cys 来贡献转亚硝化作用。对于缺乏修订基序的蛋白质，我们讨论了替代机制，包括亚硝酰谷胱甘肽作为一种转导剂的潜在作用。
