Characterization of an inducible vancomycin resistance system in Streptomyces coelicolor reveals a novel gene (vanK) required for drug resistance
Characterization of an inducible vancomycin resistance system in Streptomyces coelicolor reveals a novel gene (vanK) required for drug resistance
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DOI：
10.1111/j.1365-2958.2004.04032.x
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发表时间：
2004-05-01
影响因子：
3.6
通讯作者：
Buttner, MJ
中科院分区：
文献类型：
--
作者：
Hong, HJ;Hutchings, MI;Buttner, MJ
万古霉素是治疗耐甲氧西林金黄色葡萄球菌(MRSA)引起的问题感染的一线药物，而万古霉素耐药性的传播是一个尖锐的问题。万古霉素通过与细菌细胞壁前体的D-ALA-D-ALA末端结合来阻断肽聚糖中间体之间的交联，而D-ALA-D-ALA是转糖酶/转肽酶的底物。我们已经鉴定了天蓝色链霉菌中的一个由七个基因组成的簇(VanSRJKHAX)，这些基因赋予了可诱导的、高水平的万古霉素耐药性。VanHAX与万古霉素耐药肠球菌中发现的基因同源，这些基因编码的酶预计会重新编程肽聚糖的生物合成，使细胞壁前体终止于D-Ala-D-Lac而不是D-Ala-D-Ala。VANS和VANS编码一个双组分的信号转导系统，该系统介导七个VAN基因的转录诱导。VanJ和Vank是新的基因，在病原体的万古霉素耐药簇中没有对应的基因。Vank是Fem家族中的一员，它将跨桥氨基酸添加到细胞壁前体的茎五肽上，并且Vank在万古霉素耐药性中是必不可少的。VAN基因被组织成四个转录单位，即vanRS、vanJ、Vank和vanHAX，这些转录产物是由VanR依赖的万古霉素诱导的。为了建立一种敏感的万古霉素抗性诱导剂的生物测定方法，将VanJ的启动子与一个与卡那霉素抗性有关的报告基因融合在一起。所有被鉴定的诱导剂都是糖肽类抗生素，但膜锚定糖肽替考拉宁未能起到诱导剂的作用。对在vanRS和cseBC细胞被膜信号转导系统中存在缺陷的突变体的分析表明，这两条信号转导系统之间存在显著的串扰。
Vancomycin is the front-line therapy for treating problematic infections caused by methicillin-resistant Staphylococcus aureus (MRSA), and the spread of vancomycin resistance is an acute problem. Vancomycin blocks cross-linking between peptidoglycan intermediates by binding to the D-Ala-D-Ala termini of bacterial cell wall precursors, which are the substrate of transglycosylase/transpeptidase. We have characterized a cluster of seven genes (vanSRJKHAX) in Streptomyces coelicolor that confers inducible, high-level vancomycin resistance. vanHAX are orthologous to genes found in vancomycin-resistant enterococci that encode enzymes predicted to reprogramme peptidoglycan biosynthesis such that cell wall precursors terminate in D-Ala-D-Lac rather than D-Ala-D-Ala. vanR and vanS encode a two-component signal transduction system that mediates transcriptional induction of the seven van genes. vanJ and vanK are novel genes that have no counterpart in previously characterized vancomycin resistance clusters from pathogens. VanK is a member of the Fem family of enzymes that add the cross-bridge amino acids to the stem pentapeptide of cell wall precursors, and vanK is essential for vancomycin resistance. The van genes are organized into four transcription units, vanRS, vanJ, vanK and vanHAX, and these transcripts are induced by vancomycin in a vanR-dependent manner. To develop a sensitive bioassay for inducers of the vancomycin resistance system, the promoter of vanJ was fused to a reporter gene conferring resistance to kanamycin. All the inducers identified were glycopeptide antibiotics, but teicoplanin, a membrane-anchored glycopeptide, failed to act as an inducer. Analysis of mutants defective in the vanRS and cseBC cell envelope signal transduction systems revealed significant cross-talk between the two pathways.