Hanski E, Caparon M
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110-1093.
Proc Natl Acad Sci U S A. 1992 Jul 1;89(13):6172-6. doi: 10.1073/pnas.89.13.6172.
Binding to fibronectin has been suggested to play an important role in adherence of the group A streptococcus Streptococcus pyrogenes to host epithelial cells; however, the identity of the streptococcal fibronectin receptor has been elusive. Here we demonstrate that the fibronectin-binding property of S. pyogenes is mediated by protein F, a bacterial surface protein that binds fibronectin at high affinity. The gene encoding protein F (prtF) produced a functional fibronectin-binding protein in Escherichia coli. Insertional mutagenesis of the cloned gene generated a mutation that resulted in the loss of fibronectin-binding activity. When this mutation was introduced into the S. pyrogenes chromosome by homologous recombination with the wild-type allele, the resulting strains no longer produced protein F and lost their ability to bind fibronectin. The mutation could be complemented by prtF introduced on a plasmid. Mutants lacking protein F had a much lower capacity to adhere to respiratory epithelial cells. These results demonstrate that protein F is an important adhesin of S. pyogenes.
有人提出，与纤连蛋白结合在A组链球菌（化脓性链球菌）黏附宿主上皮细胞的过程中发挥重要作用；然而，链球菌纤连蛋白受体的身份一直难以确定。在此，我们证明化脓性链球菌的纤连蛋白结合特性是由蛋白F介导的，蛋白F是一种细菌表面蛋白，能以高亲和力结合纤连蛋白。编码蛋白F（prtF）的基因在大肠杆菌中产生了一种功能性纤连蛋白结合蛋白。对克隆基因进行插入诱变产生了一个突变，导致纤连蛋白结合活性丧失。当通过与野生型等位基因进行同源重组将此突变引入化脓性链球菌染色体时，所得菌株不再产生蛋白F，并失去了结合纤连蛋白的能力。该突变可用质粒上引入的prtF进行互补。缺乏蛋白F的突变体黏附呼吸道上皮细胞的能力要低得多。这些结果表明，蛋白F是化脓性链球菌的一种重要黏附素。
