Arthur M, Molinas C, Courvalin P
Unité des Agents Antibactériens, Institut Pasteur, Paris, France.
J Bacteriol. 1992 Apr;174(8):2582-91. doi: 10.1128/jb.174.8.2582-2591.1992.
Plasmid pIP816 of Enterococcus faecium BM4147 confers inducible resistance to vancomycin and encodes the VanH dehydrogenase and the VanA ligase for synthesis of depsipeptide-containing peptidoglycan precursors which bind the antibiotic with reduced affinity. We have characterized a cluster of five genes of pIP816 sufficient for peptidoglycan synthesis in the presence of vancomycin. The distal part of the van cluster encodes VanH, VanA, and a third enzyme, VanX, all of which are necessary for resistance. Synthesis of these enzymes was regulated at the transcriptional level by the VanS-VanR two-component regulatory system encoded by the proximal part of the cluster. VanR was a transcriptional activator related to response regulators of the OmpR subclass. VanS stimulated VanR-dependent transcription and was related to membrane-associated histidine protein kinases which control the level of phosphorylation of response regulators. Analysis of transcriptional fusions with a reporter gene and RNA mapping indicated that the VanR-VanS two-component regulatory system activates a promoter used for cotranscription of the vanH, vanA, and vanX resistance genes.
粪肠球菌BM4147的质粒pIP816赋予对万古霉素的诱导抗性，并编码用于合成含脂肽聚糖前体的VanH脱氢酶和VanA连接酶，这些前体与抗生素的结合亲和力降低。我们已经鉴定出pIP816上的五个基因簇，在万古霉素存在下足以进行肽聚糖合成。van基因簇的远端部分编码VanH、VanA和第三种酶VanX，所有这些都是抗性所必需的。这些酶的合成在转录水平上由该基因簇近端编码的VanS-VanR双组分调节系统调控。VanR是一种与OmpR亚类应答调节因子相关的转录激活因子。VanS刺激VanR依赖性转录，并且与控制应答调节因子磷酸化水平的膜相关组氨酸蛋白激酶有关。用报告基因进行转录融合分析和RNA定位表明，VanR-VanS双组分调节系统激活了用于vanH、vanA和vanX抗性基因共转录的启动子。
