title: A major portion of DNA gyrase inhibitor microcin B17 undergoes an N,O-peptidyl shift during synthesis.
abstract: Microcin B17 (McB) is a 43-amino acid antibacterial peptide targeting the DNA gyrase. The McB precursor is ribosomally produced and then post-translationally modified by the McbBCD synthase. Active mature McB contains eight oxazole and thiazole heterocycles. Here, we show that a major portion of mature McB contains an additional unusual modification, a backbone ester bond connecting McB residues 51 and 52. The modification results from an N → O shift of the Ser(52) residue located immediately downstream of one of McB thiazole heterocycles. We speculate that the N,O-peptidyl shift undergone by Ser(52) is an intermediate of post-translational modification reactions catalyzed by the McbBCD synthase that normally lead to formation of McB heterocycles.
authors.affiliation: Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Ghilarov
authors.forename: Marina
authors.initials: M
authors.lastname: Serebryakova
authors.forename: Irina
authors.initials: I
authors.lastname: Shkundina
authors.forename: Konstantin
authors.initials: K
authors.lastname: Severinov
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001430:Bacteriocins / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D059005:Topoisomerase II Inhibitors
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D059005:Topoisomerase II Inhibitors; C102057:microcin B17 synthase; C020411:microcin