Functional Characterization of the Interaction between Bacterial Adhesin Multivalent Adhesion Molecule 7 ( MAM7) Protein and Its Host Cell Ligands
Functional Characterization of the Interaction between Bacterial Adhesin Multivalent Adhesion Molecule 7 ( MAM7) Protein and Its Host Cell Ligands
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DOI：
10.1074/jbc.m111.291377
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发表时间：
2011-11-11
影响因子：
4.8
通讯作者：
Orth, Kim
中科院分区：
文献类型：
--
作者：
Krachler, Anne Marie;Orth, Kim
病原体快速与宿主细胞表面形成稳定相互作用的能力是其成功的关键。细菌病原体使用一系列毒力因子，但它们的有效使用依赖于宿主和病原体之间的密切接触。我们最近发现了一种组成型表达的MAM7（多价粘附分子7），它广泛分布于革兰氏阴性病原体中，使它们能够与宿主细胞建立初始接触。在这里，我们描述了MAM7与宿主细胞表面的相互作用的解剖成两个不同的结合事件，涉及宿主蛋白纤连蛋白和膜磷脂磷脂酸。我们分析了MAM7和纤连蛋白中的哪些结构域是复合物形成所必需的。我们进一步研究了磷脂酸结合MAM7使用定点诱变和脂质体缔合试验，并证明了MAM7上的碱性电荷的特定分布是需要高亲和力结合。最后，我们表明，纤连蛋白和磷脂酸结合MAM7是不相互排斥的，这三个分子可能组装成一个三重复合物的宿主细胞表面。
The ability of a pathogen to rapidly form a stable interaction with the host cell surface is key to its success. Bacterial pathogens use a repertoire of virulence factors, but their efficient use relies on close contact between the host and the pathogen. We have recently identified a constitutively expressed MAM7(multivalent adhesion molecule 7), which is widely distributed in Gram-negative pathogens and enables them to establish initial contact with the host cell. Here, we describe the dissection of the MAM7 interaction with the host cell surface into two distinct binding events, involving the host protein fibronectin and the membrane phospholipid phosphatidic acid. We analyzed which domains within MAM7 and fibronectin are necessary for complex formation. We further studied phosphatidic acid binding by MAM7 using site-directed mutagenesis and liposome association assays and demonstrated that a specific distribution of basic charge on MAM7 is required for high affinity binding. Finally, we showed that fibronectin and phosphatidic acid binding to MAM7 are not mutually exclusive and that the three molecules likely assemble into a tripartite complex on the host cell surface.