Clumping factor B (ClfB), a new surface-located fibrinogen-binding adhesin of Staphylococcus aureus
Clumping factor B (ClfB), a new surface-located fibrinogen-binding adhesin of Staphylococcus aureus
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DOI：
10.1046/j.1365-2958.1998.01050.x
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发表时间：
1998-10-01
影响因子：
3.6
通讯作者：
Foster, Timothy J.
中科院分区：
文献类型：
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作者：
Ni Eidhin, Deirdre;Perkins, Samuel;Foster, Timothy J.
金黄色葡萄球菌的表面纤维蛋白原结合蛋白（凝集因子; ClfA）具有将配体结合结构域连接到壁锚定区域的不寻常的二肽重复。Southern杂交实验揭示了S.金黄色葡萄球菌纽曼基因组，其与包含编码二肽重复序列的DNA的探针杂交。这里分析其中一个位点。它还编码一种纤维蛋白原结合蛋白，我们称之为ClfB。ClfB的整体结构与ClfA非常相似，并且蛋白质在信号序列和壁附着结构域中具有相当大的序列同一性。然而，A区只有26%相同。重组生物素化ClfB蛋白在蛋白质配体印迹中与纤维蛋白原结合。在配体印迹中，ClfB与纤维蛋白原的α链和β链反应，而ClfA仅与γ链结合。对S.金黄色葡萄球菌纽曼通过使用针对ClfB的重组A区产生的抗体的蛋白质免疫印迹鉴定出124 kDa的蛋白质作为clfB基因产物。这种蛋白质仅在生长到早期指数期的细胞上可检测到。它不存在于来自指数期晚期或稳定期培养物的细胞中。使用单独通过等位基因置换分离的clfB突变体和与clfA突变组合，ClfB蛋白显示促进（1）指数期细胞在纤维蛋白原溶液中的凝集，（ii）指数期细菌在体外粘附到固定的纤维蛋白原，和（iii）细菌粘附到离体人血液透析管，这表明它可能有助于生物材料相关感染的致病性。然而，在野生型指数相S。在金黄色葡萄球菌纽曼培养物中，ClfB活性被ClfA蛋白掩蔽，并且它根本不参与来自稳定期培养物的细胞与纤维蛋白原的相互作用。ClfB依赖性细菌粘附固定化纤维蛋白原被抑制的毫摩尔浓度的Ca 2+和Mn 2+，这表明，像ClfA，ClfB的配体结合是由一个低亲和力抑制性阳离子结合位点。
The surface-located fibrinogen-binding protein (clumping factor; ClfA) of Staphylococcus aureus has an unusual dipeptide repeat linking the ligand binding domain to the wall-anchored region. Southern blotting experiments revealed several other loci in the S. aureus Newman genome that hybridized to a probe comprising DNA encoding the dipeptide repeat. One of these loci is analysed here. It also encodes a fibrinogen-binding protein, which we have called ClfB. The overall organization of ClfB is very similar to that of ClfA, and the proteins have considerable sequence identity in the signal sequence and wall attachment domains. However, the A regions are only 26% identical. Recombinant biotinylated ClfB protein bound to fibrinogen in Western ligand blots. ClfB reacted with the alpha- and beta-chains of fibrinogen in the ligand blots in contrast to ClfA, which binds exclusively to the gamma-chain. Analysis of proteins released from the cell wall of S. aureus Newman by Western immunoblotting using antibody raised against the recombinant A region of ClfB identified a 124kDa protein as the clfB gene product. This protein was detectable only on cells that were grown to the early exponential phase. It was absent from cells from late exponential phase or stationary phase cultures. Using a clfB mutant Isolated by allelic replacement alone and in combination with a clfA mutation, the ClfB protein was shown to promote (1) clumping of exponential-phase cells In a solution of fibrinogen, (ii) adherence of exponential phase bacteria to immobilized fibrinogen in vitro, and (iii) bacterial adherence to ex vivo human haemodialysis tubing, suggesting that it could contribute to the pathogenicity of biomaterial-related infections. However, in wild-type exponential-phase S. aureus Newman cultures, ClfB activity was masked by the ClfA protein, and it did not contribute at all to interactions of cells from stationary-phase cultures with fibrinogen. ClfB-dependent bacterial adherence to immobilized fibrinogen was inhibited by millimolar concentrations of Ca2+ and Mn2+, which indicates that, like ClfA, ligand binding by ClfB is regulated by a low-affinity inhibitory cation binding site.