A peptide ligase and the ribosome cooperate to synthesize the peptide pheganomycin
作者:Motoyoshi Noike、Takashi Matsui、Koichi Ooya、Ikuo Sasaki、Shouta Ohtaki、Yoshimitsu Hamano、Chitose Maruyama、Jun Ishikawa、Yasuharu Satoh、Hajime Ito、Hiroyuki Morita、Tohru Dairi
DOI:10.1038/nchembio.1697
日期:2015.1
Peptide natural product backbones are typically made ribosomally or by NRPS machinery. Exploration of pheganomycin biosynthesis defines a third hybrid model in which a grasp ligase joins an NRPS product with a ribosomally produced peptide. Peptide antibiotics are typically biosynthesized by one of two distinct machineries in a ribosome-dependent or ribosome-independent manner. Pheganomycin (PGM (1)) and related analogs consist of the nonproteinogenic amino acid (S)-2-(3,5-dihydroxy-4-hydroxymethyl)phenyl-2-guanidinoacetic acid (2) and a proteinogenic core peptide, making their origin uncertain. We report the identification of the biosynthetic gene cluster from Streptomyces cirratus responsible for PGM production. Unexpectedly, the cluster contains a gene encoding multiple precursor peptides along with several genes plausibly encoding enzymes for the synthesis of amino acid 2. We identified PGM1, which has an ATP-grasp domain, as potentially capable of linking the precursor peptides with 2, and validate this hypothesis using deletion mutants and in vitro reconstitution. We document PGM1's substrate permissivity, which could be rationalized by a large binding pocket as confirmed via structural and mutagenesis experiments. This is to our knowledge the first example of cooperative peptide synthesis achieved by ribosomes and peptide ligases using a peptide nucleophile.