Protein Complexes and Proteolytic Activation of the Cell Wall Hydrolase RipA Regulate Septal Resolution in Mycobacteria
Protein Complexes and Proteolytic Activation of the Cell Wall Hydrolase RipA Regulate Septal Resolution in Mycobacteria
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DOI：
10.1371/journal.ppat.1003197
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发表时间：
2013-02-01
期刊：
影响因子：
6.7
通讯作者：
Rubin, Eric J.
中科院分区：
文献类型：
--
作者：
Chao, Michael C.;Kieser, Karen J.;Rubin, Eric J.
肽聚糖水解酶是一把双刃剑。它们是正常细胞分裂所必需的，但是当失调时，它们可以成为对细菌致命的自溶素。细菌如何确保肽聚糖水解酶仅在正确的空间和时间背景下起作用仍然是未知的。在这里，我们证明，失调转化为一个自溶素，损害细胞结构的完整性的基本分枝杆菌肽聚糖水解酶RipA。我们发现，分枝杆菌控制RipA活性通过两个相互关联的调节水平在体内蛋白质相互作用协调PG水解，而蛋白水解是必要的RipA酶活性。通过用肽聚糖合成酶抑制剂处理的RipA蛋白复合物的失调导致RipA活性过度和正确形态的损害。此外，RipA显性失活突变体或差异加工的RipA同源物的表达揭示RipA作为酶原产生，需要蛋白水解加工以获得活性。RipA加工的量在快速生长和缓慢生长的分枝杆菌之间不同，并且与这些物种中对肽聚糖水解酶活性的需求相关。总之，RipA调控的复杂图景是在生长过程中仔细控制细菌细胞壁水解的不断增长的范例的一部分，并且可能代表化疗开发的新靶点。
Peptidoglycan hydrolases are a double-edged sword. They are required for normal cell division, but when dysregulated can become autolysins lethal to bacteria. How bacteria ensure that peptidoglycan hydrolases function only in the correct spatial and temporal context remains largely unknown. Here, we demonstrate that dysregulation converts the essential mycobacterial peptidoglycan hydrolase RipA to an autolysin that compromises cellular structural integrity. We find that mycobacteria control RipA activity through two interconnected levels of regulation in vivo-protein interactions coordinate PG hydrolysis, while proteolysis is necessary for RipA enzymatic activity. Dysregulation of RipA protein complexes by treatment with a peptidoglycan synthase inhibitor leads to excessive RipA activity and impairment of correct morphology. Furthermore, expression of a RipA dominant negative mutant or of differentially processed RipA homologues reveals that RipA is produced as a zymogen, requiring proteolytic processing for activity. The amount of RipA processing differs between fast-growing and slow-growing mycobacteria and correlates with the requirement for peptidoglycan hydrolase activity in these species. Together, the complex picture of RipA regulation is a part of a growing paradigm for careful control of cell wall hydrolysis by bacteria during growth, and may represent a novel target for chemotherapy development.