The standalone aminopeptidase PepN catalyzes the maturation of blasticidin S from leucylblasticidin S.
The standalone aminopeptidase PepN catalyzes the maturation of blasticidin S from leucylblasticidin S.
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独立的氨肽酶 PepN 催化亮氨酰杀稻瘟素 S 成熟为杀稻瘟素 S
DOI：
10.1038/srep17641
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发表时间：
2015-12-01
影响因子：
4.6
通讯作者：
He X
中科院分区：
文献类型：
--
作者：
Yu G;Li L;Liu X;Liu G;Deng Z;Zabriskie MT;Jiang M;He X
从稻瘟病链霉菌中分离得到的肽基核苷类杀菌剂（blasticidin S， BS）是第一个大规模应用于稻瘟病防治的非汞杀菌剂。在BS的生物合成过程中，leucylblasicidin S （LBS）被认为是倒数第二代谢物，其抑制活性比最终产物BS低20倍。在本地菌株中也观察到以10%至90%不等的效率将LBS不完全转化为BS。一种异源产链霉菌（streptomyces livid）。在这项研究中，我们确定了LBS的BS成熟不是一个自发的过程，而是由一个独立的肽酶PepN控制的，它以pH敏感的方式水解LBS，最适合pH为7~8，但当pH低于5或高于10时，它是无活性的。从lividens链霉菌中纯化出两个相邻的PepN1和PepN2同源物。大肠杆菌的LBS水解活性相差约100倍。在WJ2中过表达pepn1可使BS产量提高100%，使LBS与BS的比值从2:1降至2:3。这项工作展示了PepN在抗生素成熟中的生物学作用的扩展，并首次报道了这种保守酶水解β酰胺键。
The peptidyl nucleoside blasticidin S (BS) isolated fromStreptomyces griseochromogeneswas the first non-mercurial fungicide used on a large scale to prevent rice blast. In the biosynthesis of BS, leucylblasticidin S (LBS) was suggested as the penultimate metabolite with 20-fold less inhibitory activity than the final product BS. Incomplete conversion of LBS to BS at a variable efficiency ranging from 10% to 90% was observed either in the native strainS. griseochromogenesor a heterologous producerStreptomyces lividansWJ2. In this study, we determined that maturation of BS from LBS is not a spontaneous process but is governed by a standalone peptidase PepN, which hydrolyzes LBS in a pH-sensitive way with most appropriate of pH 7~8 but is inactive when the pH is below 5 or above 10. PepN1 and PepN2, two neighboring PepN homologs fromStreptomyces lividanswere purified inE. colibut displayed ca.100-fold difference in LBS hydrolytic activity. Overexpression ofpepN1in WJ2 enhanced BS yield by 100% and lowered the ratio of LBS to BS from 2:1 to 2:3. This work presents the expansion of the biological role for PepN in antibiotic maturation and the first report of hydrolysis of beta amide linkage by this conserved enzyme.