Diverse thioether macrocyclized peptides through a radical SAM maturase

• 成果类型: Article
• 署名作者: Eastman, Karsten A. S.; Roberts, Andrew G.; Bandarian, Vahe
• 署名单位: Utah System of Higher Education; University of Utah
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12869
• DOI: 10.1073/pnas.2512563122
• 发表日期: 2025-08-26
• 关键词: s-adenosylmethionine; chemistry; clusters; bridge; click

摘要

Disulfide bonds stabilize many bioactive peptides, but their susceptibility to reduction under physiological conditions limits broad applicability in biotechnology. PapB is a promiscuous radical S-adenosyl-L-methionine enzyme that is involved in the maturation of PapA, which is a ribosomally produced and posttranslationally modified polypeptide. PapB introduces six thioether linkages between internal Cys residues and carbon atom that is alpha to the side-chain carboxylate of Asp/Glu residues C-terminal to the Cys residues. Herein, we show that PapB also efficiently couples an internal Cys thiol to the C-terminal carboxylate of peptides terminating in D-or beta-amino acids, forming alpha- or beta- thioether macrocycles. Moreover, PapB tolerates beta-and N-methyl amino acids within the peptide, resulting in the formation of macrocycles that are comprised entirely of unnatural amino acids, such as peptides containing all beta- residues. These findings establish PapB as a sequence-agnostic thioether ligase for efficient C-terminal macrocyclization. Our work expands the enzymatic toolbox for constructing conformationally constrained peptides for therapeutics and chemical biology.