Fischer Wolfgang, Haas Rainer
Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität, D-80336 Munich, Germany.
J Bacteriol. 2004 Feb;186(3):777-84. doi: 10.1128/JB.186.3.777-784.2004.
The RecA protein is a central component of the homologous recombination machinery and of the SOS system in most bacteria. In performing these functions, it is involved in DNA repair processes and plays an important role in natural transformation competence. This may be especially important in Helicobacter pylori, where an unusually high degree of microdiversity among strains is generated by homologous recombination. We have suggested previously that the H. pylori RecA protein is subject to posttranslational modifications that result in a slight shift in its electrophoretic mobility. Here we show that at least two genes downstream of recA are involved in this modification and that this process is dependent on genes involved in glycosylation and lipopolysaccharide biosynthesis. Site-directed mutagenesis of a putative glycosylation site results in production of an unmodified RecA protein. This posttranslational modification is not involved in membrane targeting or cell division functions but is necessary for the full function of RecA in DNA repair. Thus, it might be an adaptation to the specific requirements of H. pylori in its natural environment.
RecA蛋白是大多数细菌中同源重组机制和SOS系统的核心组成部分。在执行这些功能时，它参与DNA修复过程，并在自然转化能力中发挥重要作用。这在幽门螺杆菌中可能尤为重要，因为同源重组会在菌株间产生异常高程度的微多样性。我们之前曾提出，幽门螺杆菌RecA蛋白会发生翻译后修饰，导致其电泳迁移率略有变化。在此我们表明，recA下游至少有两个基因参与这种修饰，并且该过程依赖于参与糖基化和脂多糖生物合成的基因。对一个假定的糖基化位点进行定点诱变会产生未修饰的RecA蛋白。这种翻译后修饰不参与膜靶向或细胞分裂功能，但对于RecA在DNA修复中的完整功能是必需的。因此，它可能是幽门螺杆菌在其自然环境中的特定需求的一种适应性变化。
