title: tRNA-Dependent Aminoacylation of an Amino Sugar Intermediate in the Biosynthesis of a Streptothricin-Related Antibiotic.
abstract: The antibiotic streptothricin (ST) possesses an amino sugar bound to an l-β-lysine (β-Lys) residue via a peptide bond. The peptide bond formation has been shown to be catalyzed by a nonribosomal peptide synthetase (NRPS) during ST biosynthesis. The focus of this study is the closely related ST analogue BD-12, which carries a glycine-derived side chain rather than a β-Lys residue. Here, in Streptomyces luteocolor NBRC13826, we describe our biosynthetic studies of BD-12, which revealed that the peptide bond between the amino sugar and the glycine residue is catalyzed by a Fem-like enzyme (Orf11) in a tRNA-dependent manner rather than by an NRPS. Although there have been several reports of peptide bond-forming tRNA-dependent enzymes, to our knowledge, Orf11 is the first enzyme that can accept an amino sugar as a substrate. Our findings clearly demonstrate that the structural diversity of the side chains of ST-type compounds in nature is generated in an unusual manner via two distinct peptide bond-forming mechanisms. Moreover, the identification and functional analysis of Orf11 resulted in not only the production of new ST-related compounds, but also the provision of new insights into the structure-activity relationship of the ST-related antibiotics.
  
  
  
  The antibiotic streptothricin (ST) possesses an amino sugar bound to an l-β-lysine (β-Lys) side chain via a peptide bond formed by a nonribosomal peptide synthetase (NRPS). BD-12, an analogue of ST, carries a glycine-derived side chain rather than β-Lys, and here, we describe the BD-12-biosynthetic gene cluster from Streptomyces luteocolor NBRC13826, which contains the orf11 gene encoding a novel tRNA-dependent peptide bond-forming enzyme. The unique Fem-like enzyme (Orf11) accepts the amino sugar as a substrate and mediates the peptide formation between the amino sugar intermediate and glycine. Our studies demonstrate that the structural diversity of the side chains of ST-related compounds in nature is generated via two distinct peptide bond-forming mechanisms.
authors.affiliation: Department of Bioscience, Fukui Prefectural University, Yoshida-Gun, Fukui, Japan.
authors.forename: Chitose
authors.initials: C
authors.lastname: Maruyama
authors.affiliation: Department of Bioscience, Fukui Prefectural University, Yoshida-Gun, Fukui, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Niikura
authors.affiliation: Japan Biological Informatics Consortium (JBIC), Tokyo, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Izumikawa
authors.affiliation: Japan Biological Informatics Consortium (JBIC), Tokyo, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Hashimoto
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shin-Ya
authors.affiliation: Kitasato Institute for Life Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Komatsu
authors.affiliation: Kitasato Institute for Life Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuroda
authors.affiliation: National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sekizuka
authors.affiliation: National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Ishikawa
authors.affiliation: Department of Bioscience, Fukui Prefectural University, Yoshida-Gun, Fukui, Japan hamano@fpu.ac.jp.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Hamano
mesh_terms: D000606:Amino Sugars / Q000378:metabolism*; D049148:Aminoacylation; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D053858:Metabolic Networks and Pathways; D012343:RNA, Transfer / Q000378:metabolism*; D013302:Streptomyces / Q000201:enzymology / Q000378:metabolism*; D013309:Streptothricins / Q000096:biosynthesis*
chemical_list: D000606:Amino Sugars; D000900:Anti-Bacterial Agents; D013309:Streptothricins; D012343:RNA, Transfer