SbbR/SbbA, an Important ArpA/AfsA-Like System, Regulates Milbemycin Production in Streptomyces bingchenggensis.
SbbR/SbbA, an Important ArpA/AfsA-Like System, Regulates Milbemycin Production in Streptomyces bingchenggensis.
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SbbR/SbbA 是一种重要的 ArpA/AfsA 样系统，调节丙城链霉菌中米尔贝霉素的产生
DOI：
10.3389/fmicb.2018.01064
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发表时间：
2018
影响因子：
5.2
通讯作者：
Xiang W
中科院分区：
文献类型：
--
作者：
He H;Ye L;Li C;Wang H;Guo X;Wang X;Zhang Y;Xiang W
米尔贝霉素是一组十六元大环内酯类抗生素，广泛用作杀虫剂和驱虫剂。以前，对米尔贝霉素生物合成的转录调控的有限理解阻碍了通过调控基因工程来提高抗生素生产的努力。在此，一种新的ArpA/AfsA型系统SbbR/SbbA（SBI_08928/SBI_08929）被鉴定参与调节工业菌株S. bingchenggensis BC04. BC 04中sbbR的失活导致米尔贝霉素的产量显著降低，而sbbA的缺失增强米尔贝霉素的产量。电泳迁移率变动分析（EMSA）和DNA酶I足迹法研究表明，SbbR具有特定的DNA结合活性的milR（位于簇的米尔贝霉素生产的激活基因）和双向组织的基因sbbR和sbbA的启动子。转录分析表明，SbbR直接激活milR的转录，而抑制自身和sbbA的转录。此外，还发现了SbbR的11个新靶点，包括位于次级代谢物生物合成基因簇中的7个调控基因（例如，Sbi_08420、Sbi_08432、Sbi_09158、Sbi_00827、Sbi_01376、Sbi_09325和Sig 24 sbh）和四种公知的全局调节基因（例如，glnRsbh、wblAsbh、atrAsbh和mtrA/Bsbh）。这些数据表明，SbbR不仅是米尔贝霉素生产的直接激活剂，但也是一个多效性调节器，控制其他集群定位的调控基因和全局调控基因的表达。总之，本研究揭示了控制米尔贝霉素生物合成的上层调控系统，这不仅将扩大我们对米尔贝霉素生物合成复杂调控的理解，而且为通过遗传操作SbbR/SbbA系统来提高米尔贝霉素产量提供了基础。
Milbemycins, a group of 16-membered macrolide antibiotics, are used widely as insecticides and anthelmintics. Previously, a limited understanding of the transcriptional regulation of milbemycin biosynthesis has hampered efforts to enhance antibiotic production by engineering of regulatory genes. Here, a novel ArpA/AfsA-type system, SbbR/SbbA (SBI_08928/SBI_08929), has been identified to be involved in regulating milbemycin biosynthesis in the industrial strain S. bingchenggensis BC04. Inactivation of sbbR in BC04 resulted in markedly decreased production of milbemycin, while deletion of sbbA enhanced milbemycin production. Electrophoresis mobility shift assays (EMSAs) and DNase I footprinting studies showed that SbbR has a specific DNA-binding activity for the promoters of milR (the cluster-situated activator gene for milbemycin production) and the bidirectionally organized genes sbbR and sbbA. Transcriptional analysis suggested that SbbR directly activates the transcription of milR, while represses its own transcription and that of sbbA. Moreover, 11 novel targets of SbbR were additionally found, including seven regulatory genes located in secondary metabolite biosynthetic gene clusters (e.g., sbi_08420, sbi_08432, sbi_09158, sbi_00827, sbi_01376, sbi_09325, and sig24sbh) and four well-known global regulatory genes (e.g., glnRsbh, wblAsbh, atrAsbh, and mtrA/Bsbh). These data suggest that SbbR is not only a direct activator of milbemycin production, but also a pleiotropic regulator that controls the expression of other cluster-situated regulatory genes and global regulatory genes. Overall, this study reveals the upper-layer regulatory system that controls milbemycin biosynthesis, which will not only expand our understanding of the complex regulation in milbemycin biosynthesis, but also provide a basis for an approach to improve milbemycin production via genetic manipulation of SbbR/SbbA system.