Manning P A, Beutin L, Achtman M
J Bacteriol. 1980 Apr;142(1):285-94. doi: 10.1128/jb.142.1.285-294.1980.
The traT protein (TraTp) of the F sex factor is the product of one of the two genes involved in surface exclusion. Several detergents were examined under different conditions in order to determine their ability to solubilize TraTp from membrane vesicles. These experiments showed that TraTp behaved similar to a number of peptidoglycan-associated outer membrane proteins and that it existed in multimeric aggregates within the membrane. However, unlike other major outer membrane proteins, the amount of TraTp incorporated into the membrane was not affected by lipopolysaccharide-deficient mutants, even when mutants totally lacking the neutral sugars in their lipopolysaccharide backbone were used. TraTp wqs also examined by two-dimensional gel electrophoresis, where it ran as a discrete spot with a very basic isoelectric point. By coupling cyanogen bromide-activated dextran onto whole cells and by labeling whole cells with 125I (via lactoperoxidase), it was shown that TraTp was exposed on the cell surface. TraTp in a membrane environment was also insensitive to proteolytic attack by trypsin.
F 性因子的 traT 蛋白（TraTp）是参与表面排斥的两个基因之一的产物。在不同条件下检测了几种去污剂，以确定它们从膜泡中溶解 TraTp 的能力。这些实验表明，TraTp 的行为类似于许多与肽聚糖相关的外膜蛋白，并且它以多聚体聚集体的形式存在于膜内。然而，与其他主要外膜蛋白不同，即使使用在其脂多糖主链中完全缺乏中性糖的突变体，掺入膜中的 TraTp 量也不受脂多糖缺陷突变体的影响。还通过二维凝胶电泳检测 TraTp，它在二维凝胶电泳中作为一个具有非常碱性等电点的离散斑点迁移。通过将溴化氰活化的葡聚糖偶联到全细胞上以及通过用 125I（通过乳过氧化物酶）标记全细胞，结果表明 TraTp 暴露在细胞表面。膜环境中的 TraTp 对胰蛋白酶的蛋白水解攻击也不敏感。
