气候变化领域集成服务门户(CCPortal): Trapping a cross-linked lysine–tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB

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DOI	10.1073/pnas.2101571118
	Trapping a cross-linked lysine–tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB
	Balo A.R.; Caruso A.; Tao L.; Tantillo D.J.; Seyedsayamdost M.R.; David Britt R.
发表日期	2021
ISSN	0027-8424
卷号	118 期号:21
英文摘要	The radical S-adenosylmethionine (rSAM) enzyme SuiB catalyzes the formation of an unusual carbon–carbon bond between the sidechains of lysine (Lys) and tryptophan (Trp) in the biosynthesis of a ribosomal peptide natural product. Prior work on SuiB has suggested that the Lys–Trp cross-link is formed via radical electrophilic aromatic substitution (rEAS), in which an auxiliary [4Fe-4S] cluster (AuxI), bound in the SPASM domain of SuiB, carries out an essential oxidation reaction during turnover. Despite the prevalence of auxiliary clusters in over 165,000 rSAM enzymes, direct evidence for their catalytic role has not been reported. Here, we have used electron paramagnetic resonance (EPR) spectroscopy to dissect the SuiB mechanism. Our studies reveal substrate-dependent redox potential tuning of the AuxI cluster, constraining it to the oxidized [4Fe-4S]2+ state, which is active in catalysis. We further report the trapping and characterization of an unprecedented cross-linked Lys–Trp radical (Lys–Trp•) in addition to the organometallic Ω intermediate, providing compelling support for the proposed rEAS mechanism. Finally, we observe oxidation of the Lys–Trp• intermediate by the redox-tuned [4Fe-4S]2+ AuxI cluster by EPR spectroscopy. Our findings provide direct evidence for a role of a SPASM domain auxiliary cluster and consolidate rEAS as a mechanistic paradigm for rSAM enzyme-catalyzed carbon–carbon bond-forming reactions. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Biochemistry \| enzymology \| EPR spectroscopy \| bioinorganic chemistry \| chemical biology
语种	英语
scopus关键词	lysine; structural protein; SuiB protein; tryptophan; unclassified drug; Article; biocatalyst; biochemistry; chemical bond; electron spin resonance; electrophilicity; oxidation reduction potential; protein cross linking; protein expression; site directed mutagenesis; substitution reaction
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/238558
作者单位	Department of Chemistry, University of California, Davis, CA 95616, United States; Department of Chemistry, Princeton University, Princeton, NJ 08544, United States; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States
推荐引用方式 GB/T 7714	Balo A.R.,Caruso A.,Tao L.,等. Trapping a cross-linked lysine–tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB[J],2021,118(21).
APA	Balo A.R.,Caruso A.,Tao L.,Tantillo D.J.,Seyedsayamdost M.R.,&David Britt R..(2021).Trapping a cross-linked lysine–tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB.Proceedings of the National Academy of Sciences of the United States of America,118(21).
MLA	Balo A.R.,et al."Trapping a cross-linked lysine–tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB".Proceedings of the National Academy of Sciences of the United States of America 118.21(2021).