Maruyama Chitose, Niikura Haruka, Izumikawa Miho, Hashimoto Junko, Shin-Ya Kazuo, Komatsu Mamoru, Ikeda Haruo, Kuroda Makoto, Sekizuka Tsuyoshi, Ishikawa Jun, Hamano Yoshimitsu
Department of Bioscience, Fukui Prefectural University, Yoshida-Gun, Fukui, Japan.
Japan Biological Informatics Consortium (JBIC), Tokyo, Japan.
Appl Environ Microbiol. 2016 May 31;82(12):3640-8. doi: 10.1128/AEM.00725-16. Print 2016 Jun 15.
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.
抗生素链丝菌素（ST）具有通过肽键与L-β-赖氨酸（β-Lys）残基相连的氨基糖。在ST生物合成过程中，肽键形成已被证明是由非核糖体肽合成酶（NRPS）催化的。本研究的重点是密切相关的ST类似物BD-12，它带有甘氨酸衍生的侧链而非β-Lys残基。在此，我们在黄色链霉菌NBRC13826中描述了对BD-12的生物合成研究，结果表明氨基糖与甘氨酸残基之间的肽键是由一种Fem样酶（Orf11）以tRNA依赖的方式催化形成的，而非由NRPS催化。尽管已有多篇关于形成肽键的tRNA依赖酶的报道，但据我们所知，Orf11是第一种能够接受氨基糖作为底物的酶。我们的研究结果清楚地表明，自然界中ST型化合物侧链的结构多样性是通过两种不同的肽键形成机制以一种不寻常的方式产生的。此外，对Orf11的鉴定和功能分析不仅导致了新的ST相关化合物的产生，还为ST相关抗生素的构效关系提供了新的见解。
抗生素链丝菌素（ST）具有通过非核糖体肽合成酶（NRPS）形成的肽键与L-β-赖氨酸（β-Lys）侧链相连的氨基糖。ST的类似物BD-12带有甘氨酸衍生的侧链而非β-Lys，在此，我们描述了来自黄色链霉菌NBRC13826的BD-12生物合成基因簇，其包含编码一种新型tRNA依赖的肽键形成酶的orf11基因。独特的Fem样酶（Orf11）接受氨基糖作为底物，并介导氨基糖中间体与甘氨酸之间的肽形成。我们的研究表明，自然界中ST相关化合物侧链的结构多样性是通过两种不同的肽键形成机制产生的。
