Cobalamin-dependent radical S-adenosyl-L-methionine protein functions with a partner to successively methylate tricyclic indole alkaloid for chuangxinmycin maturation and derivatization  

作　　者：Sili Wang Jiancheng Huang Yanan Du Wei Huang Yufeng Xue Xiaokun Xu Guannan Zhong Yuanyuan Shi Bin Hong Xiaoying Bian Wen Liu 

机构地区：[1]State Key Laboratory of Chemical Biology,Shanghai Institute of Organic Chemistry,University of Chinese Academy of Sciences,Chinese Academy of Sciences,Shanghai 200032,China [2]State Key Laboratory of Microbial Technology,Shandong University,Qingdao 266237,China [3]National Health Commission(NHC)Key Laboratory of Biotechnology for Microbial Drugs,Institute of Medicinal Biotechnology,Chinese Academy of Medical Science&Peking Union Medical College,Beijing 100050,China

出　　处：《Science China Chemistry》2025年第1期308-316,共9页中国科学(化学英文版)

基　　金：supported in part by the National Key Research and Development Program of China(2022YFC2303100);the National Natural Science Foundation of China(32030002,22193070);the Shanghai Post-Doctoral Excellence Program(2022718)。

摘　　要：Cobalamin(Cbl)-dependent radical S-adenosyl-L-methionine(SAM)proteins constitute the largest collection of the radical SAM superfamily that has hundreds of thousands of individual members.Many of these proteins are involved in the biosynthesis of pharmaceutically important natural products to catalyze chemically demanding reactions.In the biosynthetic pathway of chuangxinmycin(CXM),a unique indole alkaloid antibiotic with potent anti-infective activity,functionalization of the characteristic thiopyrano[4,3,2-cd]indole scaffold by regio-and stereoselective C3-methylation is believed to rely on a Cbl-dependent radical process,which,however,remained to be reconstituted biochemically.We here report the dissection of this enzymatic process,which requires the incorporation of Cxm8,a Cbl-dependent radical SAM protein,with Cxm9,a DUF5825family protein that shares no homology to any proteins of known functions.Cxm8 and Cxm9 function together by forming an unexpected heterodimeric complex that selectively catalyzes C3-methylation of the tricyclic indole-S-hetero ring system in a successive manner,achieving CXM and a recently identified,C3-dimethylated congener.Detailed biochemical characterization,isotope labeling,structural simulation and bioinformatics analysis rationalized the catalysis of the Cxm8/Cxm9 complex and particularly the necessity of the DUF5825 protein for C3-methylase activity.This is the first example that a Cbl-dependent protein acts with a partner to exhibit radical SAM activity.

关 键 词：cbl-dependent radical SAM protein biosynthesis chuangxinmycin stereoselective methylation 

分 类 号：O62[理学—有机化学]