Hubbard C L, Gherardini F C, Bassford P J, Stamm L V
Department of Parasitology, School of Public Health, University of North Carolina, Chapel Hill 27599-7400.
Infect Immun. 1991 Apr;59(4):1521-8. doi: 10.1128/iai.59.4.1521-1528.1991.
A clone expressing a 35.5-kDa recombinant treponemal protein was isolated from a genomic DNA library constructed from Treponema pallidum street strain 14. Polyclonal antiserum raised against the recombinant protein reacted with a corresponding native protein of comparable size in T. pallidum that is specific to the pathogenic treponemes. Radiolabeling of the recombinant protein with [3H]palmitate demonstrated that it is lipid modified. Like other recently characterized T. pallidum lipoproteins, the 35.5-kDa lipoprotein partitioned into the detergent phase from T. pallidum cells fractionated with Triton X-114, suggesting that it is an integral membrane protein. Processing of the recombinant 35.5-kDa lipoprotein from a precursor form to a smaller mature form was not evident in pulse-chase experiments. However, pretreatment of Escherichia coli cells expressing the 35.5-kDa lipoprotein with inhibitors of protein processing or translocation revealed the existence of a higher-molecular-mass precursor. Gene fusion studies with the transposon TnphoA demonstrated the presence of an export signal in the 35.5-kDa lipoprotein that promotes the extracytoplasmic localization of a 35.5-kDa lipoprotein-PhoA hybrid.
从用梅毒螺旋体14型街毒株构建的基因组DNA文库中分离出一个表达35.5 kDa重组梅毒螺旋体蛋白的克隆。用该重组蛋白制备的多克隆抗血清与梅毒螺旋体中大小相当的相应天然蛋白发生反应，该天然蛋白是致病性梅毒螺旋体特有的。用[3H]棕榈酸对重组蛋白进行放射性标记表明它被脂质修饰。与其他最近鉴定的梅毒螺旋体脂蛋白一样，35.5 kDa脂蛋白在用Triton X-114分级分离的梅毒螺旋体细胞中分配到去污剂相中，表明它是一种整合膜蛋白。在脉冲追踪实验中，重组35.5 kDa脂蛋白从前体形式加工成较小的成熟形式并不明显。然而，用蛋白质加工或转运抑制剂预处理表达35.5 kDa脂蛋白的大肠杆菌细胞，揭示了存在一种高分子量前体。用转座子TnphoA进行的基因融合研究表明，35.5 kDa脂蛋白中存在一个促进35.5 kDa脂蛋白-PhoA杂种胞外定位的输出信号。
