The vancomycin resistance VanRS two-component signal transduction system of Streptomyces coelicolor
The vancomycin resistance VanRS two-component signal transduction system of Streptomyces coelicolor
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DOI：
10.1111/j.1365-2958.2005.04953.x
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发表时间：
2006-02-01
影响因子：
3.6
通讯作者：
Buttner, MJ
中科院分区：
文献类型：
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作者：
Hutchings, MI;Hong, HJ;Buttner, MJ
我们利用天蓝色链霉菌femX无效突变体的万古霉素依赖性表型，分离出一系列自发的、非药物依赖性的femX抑制突变体，这些突变体组成性地表达万古霉素抗性（货车）基因。所有的抑制突变都在vanS中，但出乎意料的是，许多被预测为功能丧失突变。证实了这一解释，构建的vanS缺失突变也导致货车基因的组成型表达，表明在没有药物的情况下，VanS负调节VanR功能。相比之下，vanS pta ackA三重突变体不能合成乙酰磷酸，不能表达货车基因，而pta ackA双突变体显示野生型，调节诱导的货车基因。这些结果表明，在不存在万古霉素的情况下，乙酰磷酸磷酸化VanR，VanS作为磷酸酶抑制VanR的水平，类似于P。在暴露于万古霉素时，VanS活性从磷酸酶转换为激酶，并诱导万古霉素抗性。In S.在天蓝色链霉菌中，货车基因由万古霉素和糖肽A47934诱导，而在丰卡链霉菌（A47934生产者）中，耐药性由A47934诱导，但不由万古霉素诱导。我们利用这种区别来取代S。coelicolor vanRS基因与S.丰卡获得的菌株具有S. toyocaensis，提供了VanS效应配体是药物本身，而不是作为药物作用的结果而积累的细胞壁生物合成中的中间体的间接证据。与此一致，我们发现细胞壁生物合成后期的非糖肽类抑制剂如默诺霉素A、杆菌肽和雷莫拉宁不是S. coelicolor VanRS系统，与肠球菌VanRS系统中获得的结果相反。
We took advantage of the vancomycin-dependent phenotype of Streptomyces coelicolor femX null mutants to isolate a collection of spontaneous, drug-independent femX suppressor mutants that expressed the vancomycin-resistance (van) genes constitutively. All of the suppressor mutations were in vanS but, unexpectedly, many were predicted to be loss-of-function mutations. Confirming this interpretation, a constructed vanS deletion mutation also resulted in constitutive expression of the van genes, suggesting that VanS negatively regulated VanR function in the absence of drug. In contrast, a vanS pta ackA triple mutant, which should not be able synthesize acetyl phosphate, failed to express the van genes, whereas a pta ackA double mutant showed wild-type, regulated induction of the van genes. These results suggest that in the absence of vancomycin, acetyl phosphate phosphorylates VanR, and VanS acts as a phosphatase to suppress the levels of VanR similar to P. On exposure to vancomycin, VanS activity switches from a phosphatase to a kinase and vancomycin resistance is induced. In S. coelicolor, the van genes are induced by both vancomycin and the glycopeptide A47934, whereas in Streptomyces toyocaensis (the A47934 producer) resistance is induced by A47934 but not by vancomycin. We exploited this distinction to replace the S. coelicolor vanRS genes with the vanRS genes from S. toyocaensis. The resulting strain acquired the inducer profile of S. toyocaensis, providing circumstantial evidence that the VanS effector ligand is the drug itself, and not an intermediate in cell wall biosynthesis that accumulates as result of drug action. Consistent with this suggestion, we found that non-glycopeptide inhibitors of the late steps in cell wall biosynthesis such as moenomycin A, bacitracin and ramoplanin were not inducers of the S. coelicolor VanRS system, in contrast to results obtained in enterococcal VanRS systems.