Beachey E H, Courtney H S
Veterans Administration Medical Center, Memphis, Tennessee 38104.
Rev Infect Dis. 1987 Sep-Oct;9 Suppl 5:S475-81. doi: 10.1093/clinids/9.supplement_5.s475.
It is now recognized that bacteria bind to and colonize mucosal surfaces in a highly selective manner. After the organisms penetrate the nonspecific mechanical and cleansing forces, ligands (or adhesins) on the surface of the bacteria interact in a lock-and-key (or induced-fit) fashion with complementary receptors on mucosal surfaces of the host. The adhesins are usually composed of proteins in the form of fimbriae or fibrillae and the receptors of glycolipids or glycoproteins. In group A streptococci the adhesin, lipoteichoic acid (LTA), is anchored to one or more proteins on the surface of the bacterial cells and interacts through its lipid moiety with fibronectin molecules deposited on and bound to the epithelial cells. In an attempt to locate the region of fibronectin recognized by LTA and group A streptococci, fibronectin was cleaved with thermolysin and the fragment mixture adsorbed with Staphylococcus aureus or Streptococcus pyogenes. Staphylococci adsorbed several high-molecular-weight fragments as well as a 28-kilodalton and a 23-kilodalton fragment, whereas S. pyogenes cells adsorbed only the 28-kilodalton fragment completely. The adsorption of the fragments by S. pyogenes was blocked by LTA. Antibodies raised against a synthetic peptide copying the NH2 terminus of fibronectin reacted in a western blot with the 28-kilodalton fragment; this result indicated that S. pyogenes and its LTA react with the NH2-terminal region of fibronectin at a site distinct from that at which S. aureus reacts. Our findings are consistent with the idea that LTA mediates the attachment of group A streptococci to fatty acid binding sites of fibronectin deposited on mucosal epithelial cells.
现在人们认识到，细菌以高度选择性的方式结合并定殖于黏膜表面。在这些微生物穿透非特异性机械和清洁力之后，细菌表面的配体（或黏附素）以锁钥（或诱导契合）方式与宿主黏膜表面的互补受体相互作用。黏附素通常由菌毛或纤丝形式的蛋白质组成，而受体则是糖脂或糖蛋白。在A组链球菌中，黏附素脂磷壁酸（LTA）锚定在细菌细胞表面的一种或多种蛋白质上，并通过其脂质部分与沉积并结合在上皮细胞上的纤连蛋白分子相互作用。为了确定LTA和A组链球菌识别的纤连蛋白区域，用嗜热菌蛋白酶切割纤连蛋白，并将片段混合物用金黄色葡萄球菌或化脓性链球菌吸附。葡萄球菌吸附了几个高分子量片段以及一个28千道尔顿和一个23千道尔顿的片段，而化脓性链球菌细胞仅完全吸附了28千道尔顿的片段。化脓性链球菌对片段的吸附被LTA阻断。针对复制纤连蛋白NH2末端的合成肽产生的抗体在蛋白质印迹中与28千道尔顿的片段发生反应；这一结果表明，化脓性链球菌及其LTA在与金黄色葡萄球菌反应位点不同的位点与纤连蛋白的NH2末端区域发生反应。我们的发现与LTA介导A组链球菌附着于沉积在黏膜上皮细胞上的纤连蛋白的脂肪酸结合位点这一观点一致。
