Balsalobre C, Juárez A, Madrid C, Mouriño M, Prenafeta A, Muñoa F J
Departamento de Microbiología, Universidad de Barcelona, Spain.
Microbiology (Reading). 1996 Jul;142 ( Pt 7):1841-6. doi: 10.1099/13500872-142-7-1841.
The Hha protein from Escherichia coli is highly similar (82%) to the YmoA protein from Yersinia enterocolitica. Both are members of a new class of proteins that modulates gene expression, probably by influencing DNA topology. In this paper, complementation of the hha mutation in E. coli by the ymoA gene from Y. enterocolitica has been studied. We show that the ymoA gene complements one of the phenotypic properties of hha mutants (high level of haemolysin production when they carry the recombinant plasmid pANN202-312) when cloned in a medium-copy-number plasmid but not when carried in a low-copy-number plasmid. Western blot analysis of the expression of YmoA in E. coli rules out inefficient expression of the protein. Surprisingly, the hha gene itself fails to complement the hha mutation when cloned in a medium-copy-number vector and causes genetic rearrangements of the E. coli chromosome as a consequence of insertion sequences mobilization.
来自大肠杆菌的Hha蛋白与来自小肠结肠炎耶尔森菌的YmoA蛋白高度相似（82%）。两者都是一类新的蛋白质成员，这类蛋白质可能通过影响DNA拓扑结构来调节基因表达。在本文中，对小肠结肠炎耶尔森菌的ymoA基因对大肠杆菌hha突变的互补作用进行了研究。我们发现，当ymoA基因克隆到中拷贝数质粒中时，它能互补hha突变体的一种表型特性（当携带重组质粒pANN202 - 312时产生高水平溶血素），但当携带在低拷贝数质粒中时则不能。对大肠杆菌中YmoA表达的蛋白质免疫印迹分析排除了该蛋白表达效率低下的可能性。令人惊讶的是，hha基因本身克隆到中拷贝数载体中时无法互补hha突变，并且由于插入序列的移动导致大肠杆菌染色体发生基因重排。
