The Staphylococcus aureus lrgAB operon modulates murein hydrolase activity and penicillin tolerance
The Staphylococcus aureus lrgAB operon modulates murein hydrolase activity and penicillin tolerance
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DOI：
10.1128/jb.182.7.1794-1801.2000
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发表时间：
2000-04-01
影响因子：
3.2
通讯作者：
Bayles, KW
中科院分区：
文献类型：
--
作者：
Groicher, KH;Firek, BA;Bayles, KW
我们实验室的前期研究表明，金黄色葡萄球菌LytSR双组分调控系统影响胞壁素水解酶的活性和自溶作用，还发现了一个由LytSR调控的双顺反子操纵子，它编码两个潜在的膜相关蛋白，命名为LrgA和LrgB，推测它们参与胞壁素水解酶活性的调控。在本研究中，产生并分析lrgAB突变株以检验该假设。酶谱和定量分析的胞壁蛋白水解酶活性表明，lrgAB突变体产生增加的细胞外胞壁蛋白水解酶活性相比，野生型菌株。通过提供反式的lrgAB基因来补充lrgAB缺陷恢复了野生型表型，表明这些基因赋予细胞外胞壁蛋白水解酶活性阴性对照。除了这些作用之外，还检查了lrgAB突变对青霉素诱导的裂解和杀伤的影响。这些研究表明，lrgAB突变增强了青霉素诱导的接近生长稳定期的细胞的计费，在该稳定期，lrgAB操纵子显示出最大表达。显示lrgAB突变对青霉素诱导的杀伤的这种作用不依赖于细胞裂解。相比之下，lrgAB突变不影响青霉素诱导的细胞生长在早期指数期，其中lrgAB表达被证明是最小的时间杀死。然而，lrgAB操纵子在早期指数期细胞中的表达抑制青霉素诱导的杀伤，再次独立于细胞裂解。本研究产生的数据表明，青霉素诱导的金黄色葡萄球菌的杀伤涉及一种新的胞壁蛋白水解酶活性调节剂。
Previous studies in our laboratory have shown that the Staphylococcus aureus LytSR two-component regulatory system affects murein hydrolase activity and autolysis, A LytSR-regulated dicistronic operon has also been identified and shown to encode two potential membrane-associated proteins, designated LrgA and LrgB, hypothesized to be involved in the control of murein hydrolase activity. In the present study, a lrgAB mutant strain was generated and analyzed to test this hypothesis. Zymographic and quantitative analysis of murein hydrolase activity revealed that the lrgAB mutant produced increased extracellular murein hydrolase activity compared to that of the wild-type strain. Complementation of the lrgAB defect by providing the lrgAB genes in trans restored the wild-type phenotype, indicating that these genes confer negative control on extracellular murein hydrolase activity, In addition to these effects, the influence of the lrgAB mutation on penicillin-induced lysis and killing was examined. These studies demonstrated that the lrgAB mutation enhanced penicillin-induced billing of cells approaching the stationary phase of growth, the time at which the lrgAB operon was shown to be maximally expressed. This effect of the lrgAB mutation on penicillin-induced killing was shown to be independent of cell lysis. In contrast, the lrgAB mutation did not affect penicillin-induced killing of cells growing in early-exponential phase, a time in which lrgAB expression was shown to be minimal. However, expression of the lrgAB operon in early-exponential-phase cells inhibited penicillin-induced killing, again independent of cell lysis. The data generated by this study suggest that penicillin-induced killing of S, aureus involves a novel regulator of murein hydrolase activity.