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Structural and Functional Analyses of the Tridomain‐Nonribosomal Peptide Synthetase FmoA3 for 4‐Methyloxazoline Ring Formation
Author(s) -
Katsuyama Yohei,
Sone Kaoru,
Harada Ayaka,
Kawai Seiji,
Urano Naoki,
Adachi Naruhiko,
Moriya Toshio,
Kawasaki Masato,
Shinya Kazuo,
Senda Toshiya,
Ohnishi Yasuo
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202102760
Subject(s) - nonribosomal peptide , adenylylation , chemistry , stereochemistry , peptide , serine , ring (chemistry) , mutagenesis , biosynthesis , enzyme , biochemistry , organic chemistry , mutation , gene
Nonribosomal peptide synthetases (NRPSs) are attractive targets for bioengineering to generate useful peptides. FmoA3 is a single modular NRPS composed of heterocyclization (Cy), adenylation (A), and peptidyl carrier protein (PCP) domains. It uses α‐methyl‐ l ‐serine to synthesize a 4‐methyloxazoline ring, probably with another Cy domain in the preceding module FmoA2. Here, we determined the head‐to‐tail homodimeric structures of FmoA3 by X‐ray crystallography ( apo ‐form, with adenylyl‐imidodiphosphate and α‐methyl‐ l ‐seryl‐AMP) and cryogenic electron microscopy single particle analysis, and performed site‐directed mutagenesis experiments. The data revealed that α‐methyl‐ l ‐serine can be accommodated in the active site because of the extra space around Ala688. The Cy domains of FmoA2 and FmoA3 catalyze peptide bond formation and heterocyclization, respectively. FmoA3’s Cy domain seems to lose its donor PCP binding activity. The collective data support a proposed catalytic cycle of FmoA3.