Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, Texas 77030, USA.
J Biol Chem. 2011 Aug 26;286(34):29797-805. doi: 10.1074/jbc.M110.214981. Epub 2011 Jun 3.
Microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) are bacterial surface proteins mediating adherence of the microbes to components of the extracellular matrix of the host. On Staphylococci, the MSCRAMMs often have multiple ligands. Consequently, we hypothesized that the Staphylococcus aureus MSCRAMM bone sialoprotein-binding protein (Bbp) might recognize host molecules other than the identified bone protein. A ligand screen revealed that Bbp binds human fibrinogen (Fg) but not Fg from other mammals. We have characterized the interaction between Bbp and Fg. The binding site for Bbp was mapped to residues 561-575 in the Fg Aα chain using recombinant Fg chains and truncation mutants in Far Western blots and solid-phase binding assays. Surface plasmon resonance was used to determine the affinity of Bbp for Fg. The interaction of Bbp with Fg peptides corresponding to the mapped residues was further characterized using isothermal titration calorimetry. In addition, Bbp expressed on the surface of bacteria mediated adherence to immobilized Fg Aα. Also, Bbp interferes with thrombin-induced Fg coagulation. Together these data demonstrate that human Fg is a ligand for Bbp and that Bbp can manipulate the biology of the Fg ligand in the host.
微生物表面成分识别黏附基质分子（MSCRAMMs）是介导微生物黏附到宿主细胞外基质成分的细菌表面蛋白。在葡萄球菌中，MSCRAMMs 通常具有多个配体。因此，我们假设金黄色葡萄球菌 MSCRAMM 骨唾液蛋白结合蛋白（Bbp）可能识别宿主的其他分子，而不仅仅是已鉴定的骨蛋白。配体筛选显示 Bbp 结合人纤维蛋白原（Fg），但不结合其他哺乳动物的 Fg。我们已经描述了 Bbp 和 Fg 之间的相互作用。使用重组 Fg 链和 Far Western 印迹和固相结合测定中的截断突变体，将 Bbp 的结合位点映射到 Fg Aα 链的残基 561-575。表面等离子体共振用于确定 Bbp 对 Fg 的亲和力。使用等温滴定量热法进一步研究了 Bbp 与对应于映射残基的 Fg 肽的相互作用。此外，细菌表面表达的 Bbp 介导对固定化 Fg Aα 的黏附。此外，Bbp 干扰凝血酶诱导的 Fg 凝固。这些数据表明人 Fg 是 Bbp 的配体，并且 Bbp 可以操纵宿主中 Fg 配体的生物学特性。
