Loss of clumping factor B fibrinogen binding activity by Staphylococcus aureus involves cessation of transcription, shedding and cleavage by metalloprotease
Loss of clumping factor B fibrinogen binding activity by Staphylococcus aureus involves cessation of transcription, shedding and cleavage by metalloprotease
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DOI：
10.1074/jbc.m102389200
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发表时间：
2001-08-10
影响因子：
4.8
通讯作者：
Foster, TJ
中科院分区：
文献类型：
--
作者：
McAleese, FM;Walsh, EJ;Foster, TJ
金黄色葡萄球菌纤维蛋白原结合蛋白聚集因子B(ClfB)在生长早期细胞表面的含量高于指数晚期细胞表面，在稳定期细胞表面几乎检测不到。ClfB-LacZ融合基因的表达表明，转录在指数期结束前停止。全球调控因子agr和sar的突变对clfB转录没有影响。静止期细胞中ClfB蛋白的丢失是由于在细胞停止生长之前表达结束，加上一些蛋白质脱落到生长介质中，以及在导致静止期的两到三次细胞分裂过程中，那些留在细胞表面的分子被稀释。在细胞表面存在两种形式的蛋白质，其中较小的一种是由N端失去一个结构域而产生的。较小形式的比例随着培养的增长而增加。金属蛋白酶金溶酶对ClfB的切割起作用。EDTA和邻菲咯啉可抑制切割，金溶素缺失突变体不发生切割。纯化的金溶酶可促进定位于细胞表面的ClfB的裂解以及ClfB的重组A结构域。在Ser(197)和Leu(198)之间和Ala(199)和Val(200)之间检测到两个切割位点。截短形式的ClfB不结合纤维蛋白原。
The fibrinogen-binding protein clumping factor B (ClfB) of Staphylococcus aureus is present on the surface of cells from the early exponential phase of growth in greater amounts than on cells from late exponential phase and is barely detectable on cells from stationary phase. Expression of a clfB-lacZ fusion indicated that transcription stopped before the end of exponential phase. Mutations in the global regulators agr and sar had no effect on clfB transcription. The loss of ClfB protein from cells in stationary phase was due to expression ending before cells stopped growing, combined with shedding of some of the protein into the growth medium and dilution of those molecules remaining on the cell surface during the two to three cell division events leading to stationary phase. Two forms of the protein occurred on the cell surface, the smaller of which was generated by loss of a domain from the N terminus. The proportion of the smaller form increased as the cultures grew. The metalloprotease aureolysin was shown to be responsible for cleavage of ClfB. Cleavage was inhibited by EDTA and o-phenanthroline and did not occur in an aureolysin-deficient mutant. Purified aureolysin promoted cleavage of cell surface-located ClfB as well as the recombinant A domain of ClfB. Cleavage was detected at two sites, one located between residues Ser(197) and Leu(198) and the other between Ala(199) and Val(200). The truncated form of ClfB did not bind fibrinogen.