Coagulase and Efb of Staphylococcus aureus Have a Common Fibrinogen Binding Motif
Coagulase and Efb of Staphylococcus aureus Have a Common Fibrinogen Binding Motif
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DOI：
10.1128/mbio.01885-15
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发表时间：
2016-01-01
期刊：
影响因子：
6.4
通讯作者：
Hoeoek, Magnus
中科院分区：
文献类型：
--
作者：
Ko, Ya-Ping;Kang, Mingsong;Hoeoek, Magnus
凝固酶（Coa）和Efb是金黄色葡萄球菌分泌的蛋白，是葡萄球菌感染的重要毒力因子。辅酶a与纤维蛋白原（Fg）相互作用，通过激活凝血酶原诱导纤维蛋白（原）凝块的形成。Efb将Fg吸引到细菌表面，形成一个屏障，保护细菌不被吞噬。本文描述了使用一系列合成肽来鉴定Coa和Efb中存在的线性Fg结合基序的变体，这些变体负责这些蛋白质的Fg结合活性。该基序代表了任何微生物蛋白鉴定的第一个Fg结合基序。在酶联免疫吸附实验中，我们首先利用重组Coa片段将Fg结合位点定位到Coa含有串联重复序列的c端无序片段上。序列分析表明，该Coa区含有较短的片段，序列与Efb中的Fg结合片段相似。丙氨酸扫描方法使我们能够识别Coa和Efb中对Fg结合至关重要的残基，并确定这两种蛋白中的Fg结合基序。在这些基序中，Fg结合所需的残基在很大程度上是保守的，因此它们构成了与Fg高亲和力结合的常见Fg结合基序的变体。确定一个特定的基序也使我们能够确定一个功能性的Fg结合寄存器，用于Coa重复序列，这与之前提出的重复单元不同。金黄色葡萄球菌感染是一个主要的健康问题，影响着全球约5000万人，每年导致约2万美国人死亡。在过去几年中，研制了一些实验性疫苗。然而，这些疫苗在临床试验中都失败了。金黄色葡萄球菌在细菌细胞周围形成Fg屏障并保护其不被清除的能力可能解释了疫苗失败的原因。此外，金黄色葡萄球菌凝固酶可以在实验脓肿模型中诱导形成纤维蛋白（原）屏障，该屏障包围并保护微菌落中的细菌不被清除。在这项研究中，我们首次鉴定了一个微生物Fg结合基序。该基序的变体存在于凝固酶和eb中。我们的研究结果为合理设计抑制剂提供了分子基础，这些抑制剂可以潜在地阻止阻塞Fg屏蔽的形成。
Coagulase (Coa) and Efb, secreted Staphylococcus aureus proteins, are important virulence factors in staphylococcal infections. Coa interacts with fibrinogen (Fg) and induces the formation of fibrin(ogen) clots through activation of prothrombin. Efb attracts Fg to the bacterial surface and forms a shield to protect the bacteria from phagocytic clearance. This communication describes the use of an array of synthetic peptides to identify variants of a linear Fg binding motif present in Coa and Efb which are responsible for the Fg binding activities of these proteins. This motif represents the first Fg binding motif identified for any microbial protein. We initially located the Fg binding sites to Coa's C-terminal disordered segment containing tandem repeats by using recombinant fragments of Coa in enzyme-linked immunosorbent assay-type binding experiments. Sequence analyses revealed that this Coa region contained shorter segments with sequences similar to the Fg binding segments in Efb. An alanine scanning approach allowed us to identify the residues in Coa and Efb that are critical for Fg binding and to define the Fg binding motifs in the two proteins. In these motifs, the residues required for Fg binding are largely conserved, and they therefore constitute variants of a common Fg binding motif which binds to Fg with high affinity. Defining a specific motif also allowed us to identify a functional Fg binding register for the Coa repeats that is different from the repeat unit previously proposed.IMPORTANCE Staphylococcus aureus infections are a major health problem that affects an estimated 50 million people globally and causes the death of about 20,000 Americans each year. A number of experimental vaccines have been developed during the past years. However, these vaccines have all failed in clinical trials. The ability of S. aureus to form an Fg shield surrounding and protecting bacterial cells from clearance may explain why the vaccines are failing. Furthermore, S. aureus coagulase can induce the formation of a fibrin(ogen) shield in experimental abscess models which surrounds and protects bacteria in the microcolony from clearance. In this study, we identified for the first time a microbial Fg binding motif. Variants of this motif are present in coagulase and Efb. Our results provide a molecular basis for the rational design of inhibitors that could potentially prevent the formation of the obstructing Fg shield.