含氨基乙烯半胱氨酸核糖体肽的生物合成与化学合成

Biosynthesis and chemical synthesis of ribosomally synthesized and posttranslationally modified peptides containing aminovinyl cysteine

核糖体肽是一类拥有化学结构和生物活性多样性的多肽天然产物家族,在药物开发方面具有巨大的发展潜力。氨基乙烯半胱氨酸(AviCys)是部分核糖体肽类天然产物中存在的一种特殊C末端交联结构单元。含有AviCys单元的核糖体肽类天然环肽往往具有优良的抗菌或抗肿瘤活性,且AviCys大环结构对其生物活性至关重要。本文围绕此类天然环肽的生物合成和化学合成进行了总结:①羊毛硫肽、lipolanthines、linaridins和thioamitides四类核糖体肽天然产物中AviCys结构单元的生物合成研究进展,主要包括C末端半胱氨酸的氧化脱羧反应,丝氨酸/苏氨酸或半胱氨酸脱水或脱硫反应,以及AviCys环化反应;②针对含AviCys结构单元环肽的化学合成方法,包括自由基硫醇-炔偶联、氧化脱羧/脱羰、酰胺与缩醛缩合等。本综述同时对相关研究中存在的若干挑战和尚待解决的问题进行了梳理和总结,包括生物合成过程中尚未得到深入解析的环化步骤、化学合成中尚未解决的立体选择性和化学兼容性等。综上,对含AviCys结构单元天然环肽的生物合成途径全面解析及化学合成方法的开发,有望为此类生物功能环肽及其衍生物的制备与生物工程改造奠定基础,推动该类功能环肽在生命科学和药物科学领域的应用。

Ribosomally synthesized and post-translationally modified peptides(RiPPs)are a major class of peptide natural products that often contain noncanonical amino acids and structural motifs with promising potential as drug leads.One unique structural unit found in RiPPs is the C-terminal S-[(Z)-2-aminoethenyl]-D-cysteine(AviCys)or(2S,3S)-S-[(Z)-2-aminoethenyl]-3-methyl-D-cysteine(AviMeCys).Avi(Me)Cys-containing RiPPs usually exhibit potent antimicrobial or anticancer activities,which strictly require the presence of the C-terminal AviCys motifs.Despite the potential of Avi(Me)Cys-containing RiPPs as drug leads,lack of synthetic methods and biosynthetic systems to access these type of cyclic peptides impede the application of Avi(Me)Cys-containing peptides in medicinal chemistry.In this review,we summarize the current understanding of the biosynthesis of Avi(Me)Cys-containing peptides and the progress made in the development of chemical methods to synthesize Avi(Me)Cys motifs and derivatives.This review contains two following major sections:①The biosynthetic process of Avi(Me)Cys motifs in the different families of Avi(Me)Cys-containing RiPPs,including lanthipeptides,lipolanthines,linaridins and thioamitides,are introduced with three essential enzymatic steps:first,a cysteine decarboxylase oxidatively decarboxylated the C-terminal cysteine,generating a highly reactive enethiol;subsequently,distinct enzymes catalyze the dehydration of a serine/threonine(Ser/Thr)residue or the dethiolation of a Cys residue in the precursor peptide by incorporating a dehydroalanine(Dha)or dehydrobutyrine(Dhb)residue;finally,a putative cyclase catalyzes the Michael-type addition between the enethiol group and a Dha/Dhb residue to yield the Avi(Me)Cys motif.Detailed enzymatic investigation of these biosynthetic steps are introduced.②The chemical synthesis of the Avi(Me)Cys building block and their analogues via diverse synthetic methodology,including the radical thiol-yne coupling,the oxidative decarboxylation/decarbonylation,and the condensation of amides with acetals.Overall,further elucidation of the complete biosynthetic pathway for Avi(Me)Cys motifs in related RiPPs,along with advancements in the chemical synthesis of Avi(Me)Cys-containing natural product peptides,will facilitate the effective utilization of these bioactive peptide natural products.