Decreased amounts of cell wall-associated protein A and fibronectin-binding proteins in Staphylococcus aureus sarA mutants due to up-regulation of extracellular proteases
Decreased amounts of cell wall-associated protein A and fibronectin-binding proteins in Staphylococcus aureus sarA mutants due to up-regulation of extracellular proteases
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DOI：
10.1128/iai.69.8.4742-4748.2001
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发表时间：
2001-08-01
影响因子：
3.1
通讯作者：
Arvidson, S
中科院分区：
文献类型：
--
作者：
Karlsson, A;Saravia-Otten, P;Arvidson, S
已有数据表明，金黄色葡萄球菌细胞表面蛋白可被同一细菌产生的胞外蛋白酶降解。我们发现，在产生大量四种主要胞外蛋白酶（葡萄球菌丝氨酸蛋白酶[V8蛋白酶][SspA]、半胱氨酸蛋白酶[SspB]、金黄色素溶血素[金属蛋白酶][Aur]和葡萄球菌蛋白酶[Scp]）的sarA突变细胞中，细胞结合的纤连蛋白结合蛋白（FnBP）和蛋白A的水平与对照组相比非常低。尽管相应基因的转录未改变或增加，但它们与野生型细胞的情况相同。在全局蛋白酶抑制剂 α (2)-巨球蛋白存在下培养 sarA 突变细胞，导致细胞结合的 FnBP 增加 16 倍，表明细胞外蛋白酶是 sarA 突变细胞中 FnBP 数量减少的原因。蛋白酶抑制剂E64对FnBPs的水平没有影响，表明半胱氨酸蛋白酶不参与其中。原型金黄色葡萄球菌菌株 8325-4 中的 ssp 或 our 失活导致细胞结合的 FnBP 数量增加三倍。 8325-4 sarA突变体中相同蛋白酶基因的失活导致细胞结合蛋白A增加10至20倍。由于丝氨酸蛋白酶需要金溶素才能激活，因此可以得出结论，丝氨酸蛋白酶是细胞结合FnBP和蛋白A释放中最重要的蛋白酶。
Data have been presented indicating that Staphylococcus aureus cell surface protein can be degraded by extracellular proteases produced by the same bacterium. We have found that in sarA mutant cells, which produce high amounts of four major extracellular proteases (staphylococcal serine protease [V8 protease] [SspA], cysteine protease [SspB], aureolysin [metalloprotease] [Aur], and staphopain [Scp]), the levels of cell-bound fibronectin-binding proteins (FnBPs) and protein A were very low compared to those of wild-type cells, in spite of unaltered or increased transcription of the corresponding genes. Cultivation of sarA mutant cells in the presence of the global protease inhibitor alpha (2)-macroglobulin resulted in a 16-fold increase in cell-bound FnBPs, indicating that extracellular proteases were responsible for the decreased amounts of FnBPs in sarA mutant cells. The protease inhibitor E64 had no effect on the level of FnBPs, indicating that cysteine proteases were not involved. Inactivation of either ssp or our in the prototype S. aureus strain 8325-4 resulted in a threefold increase in the amount of cell-bound FnBPs. Inactivation of the same protease genes in a sarA mutant of 8325-4 resulted in a 10- to 20-fold increase in cell-bound protein A. As the serine protease requires aureolysin to be activated, it can thus be concluded that the serine protease is the most important protease in the release of cell-bound FnBPs and protein A.