EXPRESSION AND FUNCTION OF BACTERIAL CELL SURFACE COMPONENTS

多糖，或O抗原(O-Ag)，部分 沙门氏菌脂多糖在沙门氏菌感染中起重要作用 宿主体液系统杀死这些细菌。具体来说， O-Ag结构直接影响反应的速度和程度。 补体成分C3b在细胞表面的沉积 通过影响沉积的C3b的初始量和 影响该C3b与因子b的后续相互作用。 O-Ag结构不影响结合C3b的失活。 同样，沙门氏菌表面O-Ag的大小和密度 蒙得维的亚细胞对杀戮的程度负责 用正常人血清培养细胞。血清中的存活率与 与含有至少4-5个亚基的O-Ag侧链的脂多糖 长度和大约20%的脂多糖核心被取代 具有长度大于14个亚基的O-Ag侧链。它是 提出O-Ag通过提供血清抵抗力的功能 空间上阻碍C5b-9复合体进入细胞 薄膜。 在5 mM水杨酸钠存在下培养的大肠杆菌细胞 对多种抗生素产生表型抗药性。这 在加入水杨酸盐后5分钟内开始产生抗药性 并且不涉及蛋白质模式的显著变化 或从外膜分离的内毒素。我们已经开发出一种 化验表明水杨酸盐诱导的耐药性是由于 外膜通透性下降75%-80%。

The polysaccharide, or O-antigen (O-Ag), portion of lipopolysaccharide (LPS) of Salmonellae plays a crucial role in the killing of these bacteria by the host humoral system. Specifically, the O-Ag structure directly effects the rate and extent of deposition of the complement component C3b on the cell surface by affecting the initial amount of C3b deposited and by influencing the subsequent interaction of this C3b with factor b. O-Ag structure does not influence the inactivation of bound C3b. Similarly, the O-Ag size and density on the surface of Salmonellae montevideo cells is responsible for the extent of killing of the cells by normal human serum. Survival in serum was associated with LPS that contained O-Ag side chains of at least 4-5 subunits in length and with about 20% of the LPS cores being substituted with O-Ag side chains of length more than 14 subunits. It is proposed that the O-Ag functions to provide serum resistance by sterically hindering access of the C5b-9 complex to the cell membrane. E. coli cells grown in the presence of 5 mM sodium salicylate become phenotypically resistant to a variety of antibiotics. This resistance begins within 5 minutes after the addition of salicylate and does not involve marked alterations in the pattern of protein or LPS isolated from the outer membrane. We have developed an assay to show that the salicylate-induced drug resistance is due to a 75-80% decrease in the permeability of the outer membrane.