Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.
Chembiochem. 2018 Oct 4;19(19):2045-2048. doi: 10.1002/cbic.201800315. Epub 2018 Aug 7.
MS-271, produced by Streptomyces sp. M-271, is a lasso peptide natural product comprising 21 amino acid residues with a d-tryptophan at its C terminus. Because lasso peptides are ribosomal peptides, the biosynthesis of MS-271, especially the mechanism of d-Trp introduction, is of great interest. The MS-271 biosynthetic gene cluster was identified by draft genome sequencing of the MS-271 producer, and it was revealed that the precursor peptide contains all 21 amino acid residues including the C-terminal tryptophan. This suggested that the d-Trp residue is introduced by epimerization. Genes for modification enzymes such as a macrolactam synthetase (mslC), precursor peptide recognition element (mslB1), cysteine protease (mslB2), disulfide oxidoreductases (mslE, mslF), and a protein of unknown function (mslH) were found in the flanking region of the precursor peptide gene. Although obvious epimerase genes were absent in the cluster, heterologous expression of the putative MS-271 cluster in Streptomyces lividans showed that it contains all the necessary genes for MS-271 production including a gene for a new peptide epimerase. Furthermore, a gene-deletion experiment indicated that MslB1, -B2, -C and -H were indispensable for MS-271 production and that some interactions of the biosynthetic enzymes were essential for the biosynthesis of MS-271.
MS-271 是由链霉菌 M-271 产生的一种套索肽天然产物，由 21 个氨基酸残基组成，C 末端为 d-色氨酸。由于套索肽是核糖体肽，因此 MS-271 的生物合成，特别是 d-Trp 引入的机制，非常有趣。通过对 MS-271 产生菌的草图基因组测序，鉴定了 MS-271 的生物合成基因簇，结果表明前体肽包含所有 21 个氨基酸残基，包括 C 末端色氨酸。这表明 d-Trp 残基是通过差向异构化引入的。在前体肽基因的侧翼区域发现了修饰酶基因，如大环内酯合酶（mslC）、前体肽识别元件（mslB1）、半胱氨酸蛋白酶（mslB2）、二硫键氧化还原酶（mslE、mslF）和一个未知功能的蛋白（mslH）。尽管该簇中没有明显的差向异构酶基因，但在链霉菌 lividans 中外源表达假定的 MS-271 簇表明，它包含 MS-271 生产所需的所有基因，包括一个新的肽差向异构酶基因。此外，基因缺失实验表明，MslB1、-B2、-C 和 -H 对于 MS-271 的产生是不可或缺的，并且生物合成酶的一些相互作用对于 MS-271 的生物合成是必不可少的。
