Gless Bengt H, Schmied Sabrina H, Olsen Christian A
Center for Biopharmaceuticals and Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, DK-2100, Copenhagen, Denmark.
JACS Au. 2025 Jan 10;5(1):67-72. doi: 10.1021/jacsau.4c01143. eCollection 2025 Jan 27.
Cysteine thioesters are involved in a myriad of central biological transformations due to their unique reactivity. Despite their well-studied properties, we discovered an unexpected transamidation reaction of cysteine thioesters that leads to peptide backbone cleavage. -Acylcysteine-containing peptides were found to spontaneously fragment by cleavage of the amide bond in the -1 position to the acylated cysteine residue at pH 8-10. We present compelling evidence of a mechanism involving a central reversible thioester-to-imide acyl transfer step. The discovered transamidation reaction was found to be highly sequence dependent and to occur in peptides containing post-translational modifications (PTMs) such as cysteine S-acetylation and S-palmitoylation as well as in peptide-peptide branched thioesters, mimicking class I intein splicing. Thus, the inherent reactivity of peptide backbones containing -acylcysteine residues should represent a starting point for investigation of endogenous protein behavior and may serve as a foundation for the discovery of mild new peptide and protein transformations.
由于其独特的反应性，半胱氨酸硫酯参与了无数核心生物转化过程。尽管其性质已得到充分研究，但我们发现了半胱氨酸硫酯意外的转酰胺反应，该反应会导致肽主链断裂。发现在pH 8 - 10条件下，含β-酰基半胱氨酸的肽会通过酰化半胱氨酸残基-1位的酰胺键断裂而自发断裂。我们提供了有力证据，证明其机制涉及一个关键的可逆硫酯到酰亚胺的酰基转移步骤。发现所发现的转酰胺反应高度依赖序列，且发生在含有翻译后修饰（PTM）（如半胱氨酸S - 乙酰化和S - 棕榈酰化）的肽以及肽 - 肽支链硫酯中，类似于I类内含肽剪接。因此，含有β-酰基半胱氨酸残基的肽主链的固有反应性应成为研究内源性蛋白质行为的起点，并可能为发现温和的新型肽和蛋白质转化奠定基础。
