Contribution of the Staphylococcus aureus Atl AM and GL murein hydrolase activities in cell division, autolysis, and biofilm formation.
Contribution of the Staphylococcus aureus Atl AM and GL murein hydrolase activities in cell division, autolysis, and biofilm formation.
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DOI：
10.1371/journal.pone.0042244
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Bayles KW
中科院分区：
文献类型：
--
作者：
Bose JL;Lehman MK;Fey PD;Bayles KW
金黄色葡萄球菌最主要的毛霉素水解酶ATLA是一种双功能酶，它通过蛋白水解酶产生两种具有催化活性的蛋白质，即酰胺酶(AM)和氨基葡萄糖苷酶(GL)。虽然ATLA的双功能特性早已被认识到，但大多数研究都集中在该蛋白在细胞壁代谢和生物膜发育中的联合功能。在这项研究中，我们获得了临床分离的金黄色葡萄球菌UAMS-1的突变衍生物，其中ATLA的AM和GL结构域中的一个或两个已经缺失。对这些菌株的检测表明，每个突变体的生长速度与亲本菌株相当，但表现出与亲本菌株不同的聚集表型和裂解图谱，表明它们在细胞壁代谢中发挥着不同的作用。鉴于自溶在作为生物膜基质分子的基因组DNA释放中的已知功能，我们也在生物膜检测中测试了突变体，发现AM和GL都是生物膜发育所必需的。此外，使用酶失活的点突变显示AM和GL都必须是催化活性的，才能使金黄色葡萄球菌形成生物膜。本研究结果揭示了AM和GL在金黄色葡萄球菌中的相对作用，并证实了ATL介导的裂解作用在生物膜发育中的作用。
The most prominent murein hydrolase of Staphylococcus aureus, AtlA, is a bifunctional enzyme that undergoes proteolytic cleavage to yield two catalytically active proteins, an amidase (AM) and a glucosaminidase (GL). Although the bifunctional nature of AtlA has long been recognized, most studies have focused on the combined functions of this protein in cell wall metabolism and biofilm development. In this study, we generated mutant derivatives of the clinical S. aureus isolate, UAMS-1, in which one or both of the AM and GL domains of AtlA have been deleted. Examination of these strains revealed that each mutant exhibited growth rates comparable to the parental strain, but showed clumping phenotypes and lysis profiles that were distinct from the parental strain and each other, suggesting distinct roles in cell wall metabolism. Given the known function of autolysis in the release of genomic DNA for use as a biofilm matrix molecule, we also tested the mutants in biofilm assays and found both AM and GL necessary for biofilm development. Furthermore, the use of enzymatically inactive point mutations revealed that both AM and GL must be catalytically active for S. aureus to form a biofilm. The results of this study provide insight into the relative contributions of AM and GL in S. aureus and demonstrate the contribution of Atl-mediated lysis in biofilm development.
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