Characterization of biosynthetic gene cluster for the production of virginiamycin M, a streptogramin type A antibiotic, in Streptomyces virginiae
Characterization of biosynthetic gene cluster for the production of virginiamycin M, a streptogramin type A antibiotic, in Streptomyces virginiae
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DOI：
10.1016/j.gene.2006.12.035
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发表时间：
2007-05-15
期刊：
影响因子：
3.5
通讯作者：
Nihira, Takuya
中科院分区：
文献类型：
--
作者：
Pulsawat, Nattika;Kitani, Shigeru;Nihira, Takuya
维吉尼亚霉素M（VM）是维吉尼亚链霉菌（Streptomyces virginiae）的一种杂合聚酮-肽类抗生素，与肽类抗生素维吉尼亚霉素S（VS）具有协同作用。VM和VS属于Streptogramin家族，其特点是具有很强的协同抗菌活性，其水溶性衍生物是对抗万古霉素耐药革兰氏阳性菌的新的治疗选择。在此，VM生物合成基因簇从S. virginiae在位于virginiamycin生产调节岛附近的62-kb区域中。序列分析表明，该区域由19个完整的开放阅读框（ORF）和1个C端截短的ORF组成，编码杂合聚酮合酶（PKS）-非核糖体肽合成酶（NRPS）、典型的PKS、VM前体合成酶、抗性转运蛋白、调节蛋白和辅助酶。通过对编码杂合PKS-NRPS大合成酶的virA进行基因破坏，证实了克隆的基因簇参与VM生物合成，这导致VM生产完全丧失，而对VS生产没有任何影响。为了组装VM核心结构，VirA，VirF，VirG和VirH组成的，作为一个整体，在8个PKS模块和7个结构域在2个NRPS模块中的24个结构域被预测作为一个酰基转移酶（AT）-少杂合PKS-NR-PS，而VirB，VirC，VirD和维雷可能是必不可少的甲基基团的VM框架的HMG-CoA酶为基础的反应。在VM基因簇中基因组织的几个不常见的特征中，每个PKS模块中缺乏AT结构域和存在由virl编码的离散AT是值得注意的。由ermEp* 驱动的virl的额外拷贝的AT过表达导致VM产量增加1.5倍，表明Virl的量部分限制VM生物合成。(C)2007 Elsevier B. V.保留所有权利。
Virginiamycin M (VM) of Streptomyces virginiae is a hybrid polyketide-peptide antibiotic with peptide antibiotic virginiamycin S (VS) as its synergistic counterpart. VM and VS belong to the Streptogramin family, which is characterized by strong synergistic antibacterial activity, and their water-soluble derivatives are a new therapeutic option for combating vancomycin-resistant Gram-positive bacteria. Here, the VM biosynthetic gene cluster was isolated from S. virginiae in the 62-kb region located in the vicinity of the regulatory island for virginiamycin production. Sequence analysis revealed that the region consists of 19 complete open reading frames (ORFs) and one C-terminally truncated ORF, encoding hybrid polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS), typical PKS, enzymes synthesizing precursors for VM, transporters for resistance, regulatory proteins, and auxiliary enzymes. The involvement of the cloned gene cluster in VM biosynthesis was confirmed by gene disruption of virA encoding a hybrid PKS-NRPS megasynthetase, which resulted in complete loss of VM production without any effect on VS production. To assemble the VM core structure, VirA, VirF, VirG, and VirH consisting, as a whole, of 24 domains in 8 PKS modules and 7 domains in 2 NRPS modules were predicted to act as an acyltransferase (AT)-less hybrid PKS-NR-PS, whereas VirB, VirC, VirD, and VirE are likely to be essential for the incorporation of the methyl group into the VM framework by a HMG-CoA synthase-based reaction. Among several uncommon features of gene organization in the VM gene cluster, the lack of AT domain in every PKS module and the presence of a discrete AT encoded by virl are notable. AT-overexpression by an additional copy of virl driven by ermEp* resulted in 1.5-fold increase of VM production, suggesting that the amount of Virl is partly limiting VM biosynthesis. (C) 2007 Elsevier B.V. All rights reserved.