Wang Xiankun, Du Aiqin, Yu Guiyang, Deng Zixin, He Xinyi
State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong UniversityShanghai, China.
Front Microbiol. 2017 Aug 22;8:1565. doi: 10.3389/fmicb.2017.01565. eCollection 2017.
The peptidyl nucleoside blasticidin S (BS) produced by was the first non-mercurial fungicide used to prevent rice blast and increasingly used as a selection reagent in transgenic study. Acylation by addition of a leucine residue at the beta amine group of arginine side chain of demethylblasticidin S (DBS) has been proposed as a novel self-resistance to the cytotoxic biosynthetic intermediate. But the resultant product leucyldemethylblasticidin S (LDBS) has not been isolated as a metabolite, and LDBS synthetase activity remained to be demonstrated in . In this study, we isolated LDBS in a BS heterologous producer WJ2 upon the deletion of , which encodes a S-Adenosyl methionine-dependent methyltransferase. Purified BlsL efficiently methylated LDBS at the delta N of beta-arginine to generate the ultimate intermediate LBS, but nearly didn't methylate DBS to final product BS. Above experiments demonstrated that LDBS is indeed an intermediate in BS biosynthetic pathway, and acylation of beta-amino group of arginine side chain is prerequisite for efficient guanidine -methylation in addition to being a self-resistance mechanism.
由 产生的肽基核苷杀稻瘟菌素S（BS）是第一种用于预防稻瘟病的非汞类杀菌剂，并越来越多地用作转基因研究中的选择试剂。有人提出，通过在去甲基杀稻瘟菌素S（DBS）精氨酸侧链的β胺基上添加亮氨酸残基进行酰化，是对细胞毒性生物合成中间体的一种新型自我抗性。但所得产物亮氨酰去甲基杀稻瘟菌素S（LDBS）尚未作为代谢产物分离出来，并且在 中LDBS合成酶活性仍有待证明。在本研究中，我们在缺失 （其编码一种依赖S-腺苷甲硫氨酸的甲基转移酶）的BS异源产生菌WJ2中分离出了LDBS。纯化的BlsL能有效地将LDBS的β-精氨酸的δN甲基化，生成最终中间体LBS，但几乎不能将DBS甲基化生成最终产物BS。上述实验表明，LDBS确实是BS生物合成途径中的一个中间体，精氨酸侧链β-氨基的酰化除了作为一种自我抗性机制外，还是高效胍基甲基化的先决条件。
