Kuusela P, Vartio T, Vuento M, Myhre E B
Infect Immun. 1984 Aug;45(2):433-6. doi: 10.1128/iai.45.2.433-436.1984.
Purified cathepsin G fragments of fibronectin were used to locate the binding sites for streptococci and staphylococci in the fibronectin molecule. The iodinated, NH2-terminal, 30-kilodalton (kd) fragment bound to group A and G streptococci and to Staphylococcus aureus. The 125I-labeled, COOH-terminal, 120- to 140-kd fragment bound weakly to group A streptococcus strain and to S. aureus when tested in a buffer of low ionic strength. The 30- and 120- to 140-kd fragments inhibited the binding of iodinated fragments to bacteria. The two fragments were, on a molar basis, equally effective, and they were more potent inhibitors than intact fibronectin. The gelatin-binding 40-kd fragment neither bound to any of the bacterial strains nor inhibited the binding of 125I-labeled 30-kd or 125I-labeled 120- to 140-kd fragments to bacteria. The results indicate that fibronectin has at least two separate binding sites for streptococci and staphylococci, one in the NH2-terminal region and another in the COOH-terminal region of the molecule, both capable of specific interaction with a complementary structure exposed on streptococcal and staphylococcal cell surfaces.
纤连蛋白的纯化组织蛋白酶G片段被用于定位纤连蛋白分子中链球菌和葡萄球菌的结合位点。碘化的、氨基末端的30千道尔顿（kd）片段与A组和G组链球菌以及金黄色葡萄球菌结合。在低离子强度缓冲液中进行测试时，125I标记的羧基末端120至140kd片段与A组链球菌菌株和金黄色葡萄球菌的结合较弱。30kd和120至140kd片段抑制碘化片段与细菌的结合。这两个片段在摩尔基础上具有同等效力，并且它们是比完整纤连蛋白更有效的抑制剂。与明胶结合的40kd片段既不与任何细菌菌株结合，也不抑制125I标记的30kd或125I标记的120至140kd片段与细菌的结合。结果表明，纤连蛋白在链球菌和葡萄球菌上至少有两个独立的结合位点，一个在分子的氨基末端区域，另一个在羧基末端区域，两者都能够与链球菌和葡萄球菌细胞表面暴露的互补结构发生特异性相互作用。
