EXPRESSION AND FUNCTION OF BACTERIAL CELL SURFACE COMPONENTS

急诊大肠杆菌K1荚膜参与致病过程， 毒性和侵袭性。 我们发现K1囊表达 细菌细胞表面的合成需要孔蛋白的存在 外膜中的蛋白质。 一种特殊的孔蛋白，蛋白K，在所有 K1包囊菌株，能够支持K1的更快速表达 胶囊相比，其他孔蛋白测试。 然而，没有 K1胶囊在含有以下物质的菌株中的稳态量增加 蛋白K 因此，蛋白K可能在组织细胞中更有效。 推测的外膜复合物参与细胞外转运， K1胶囊 细菌被巨噬细胞摄入并降解。 但某些 细菌成分如LPS可在体内持续数天， 巨噬细胞吞噬后。 外膜蛋白也存在。 它 值得注意的是，这些蛋白质与细胞内的LPS相关， 它们的持续存在很可能反映了这种联系。 的 抗降解的细菌组分随后可以循环， 用于抗原呈递的细胞表面。 外膜内脂多糖的O-PS部分调节着细胞内的 补体成分C3 b的沉积程度，因此调节 巨噬细胞吞噬这些细胞的速率。 相对次要 在各种菌株中发现的不同O-PS结构的变化可能 对这些细胞的清除有深远的影响，从而改变它们的 在小鼠中的毒性。 在这一过程中，项目事务处通过影响 通过改变补体的结合， 因子B。从而增加C3 b的沉积。

The E. coli K1 capsule is involved in pathogenic processes such as virulence and invasiveness. We find that expression of K1 capsule synthesis on the bacterial cell surface requires the presence of porin proteins in the outer membrane. A specific porin, protein K, found in all K1 encapsulated strains, is able to support the more rapid expression of K1 capsule as compared to other porin proteins tested. There was, however, no increase in the steady state amount of K1 capsule in strains containing protein K. Thus, protein K may be more efficient in the organization of a putative outer membrane complex involved in the extracellular transport on the K1 capsule. Bacteria are ingested and degraded by macrophages. However, certain bacterial components such as LPS may persist for several days within the macrophage after phagacytosis. Outer membrane proteins also persist. It is notable that these proteins are associated with LPS within the cell and their persistence may well be a reflection of this association. The bacterial components resistant to degradation may subsequently be cycled to the cell surface for antigen presentation. The O-PS portion of LPS in the outer membrane of Salmonellae regulates the extent of deposition of the complement component C3b and hence regulates the rate of phagacytosis of these cells by macrophages. Relatively minor changes in the structure of different O-PS found in various strains may have profound effects on the clearance of these cells and thus alter their virulence in mice. The O-PS functions in this process by influencing the activation of complement by the alternate pathway by altering the binding of factor B. and hence the amplification of deposition of C3b.