Radolf J D
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235-9113, USA.
Mol Microbiol. 1995 Jun;16(6):1067-73. doi: 10.1111/j.1365-2958.1995.tb02332.x.
Treponema pallidum, the syphilis spirochaete, has a remarkable ability to evade the humoral and cellular responses it elicits in infected hosts. Although formerly attributed to the presence of an outer coat comprised of serum proteins and/or mucopolysaccharides, current evidence indicates that the immuno-evasiveness of this bacterium is largely the result of its unusual molecular architecture. Based upon a combination of molecular, biochemical, and ultrastructural data, it is now believed that the T. pallidum outer membrane (OM) contains a paucity of poorly immunogenic transmembrane proteins ('rare outer membrane proteins') and that its highly immunogenic proteins are lipoproteins anchored predominantly to the periplasmic leaflet of the cytoplasmic membrane. The presence in the T. pallidum OM of a limited number of transmembrane proteins has profound implications for understanding syphilis pathogenesis as well as treponemal physiology. Two major strategies for molecular characterization of rare outer membrane proteins have evolved. The first involves the identification of candidate OM proteins as fusions with Escherichia coli alkaline phosphatase. The second involves the characterization of candidate OM proteins identified in outer membranes isolated from virulent T. pallidum. Criteria to define candidate OM proteins and for definitive identification of rare OM proteins are proposed as a guide for future studies.
梅毒螺旋体，即引起梅毒的螺旋菌，具有非凡的能力来逃避其在受感染宿主体内引发的体液和细胞免疫反应。虽然以前认为这是由于存在由血清蛋白和/或粘多糖组成的外层包膜，但目前的证据表明，这种细菌的免疫逃避主要是其独特分子结构的结果。基于分子、生化和超微结构数据的综合分析，现在认为梅毒螺旋体外膜（OM）含有少量免疫原性较差的跨膜蛋白（“稀有外膜蛋白”），并且其高免疫原性蛋白是主要锚定在细胞质膜周质小叶上的脂蛋白。梅毒螺旋体OM中存在数量有限的跨膜蛋白，这对理解梅毒发病机制以及螺旋体生理学具有深远意义。已发展出两种用于稀有外膜蛋白分子表征的主要策略。第一种方法是将候选OM蛋白鉴定为与大肠杆菌碱性磷酸酶的融合蛋白。第二种方法是对从有毒力的梅毒螺旋体分离的外膜中鉴定出的候选OM蛋白进行表征。提出了定义候选OM蛋白和明确鉴定稀有OM蛋白的标准，作为未来研究的指南。
