Hirokawa K, Ogino T, Aiba H, Mizuno T
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Japan.
Biosci Biotechnol Biochem. 1996 Oct;60(10):1681-5. doi: 10.1271/bbb.60.1681.
In Escherichia coli, expression of the major outer membrane proteins, OmpC and OmpF, is regulated in response to the medium osmolarity and other environmental stimuli. A two-component signal transduction system, mediated by EnvZ and OmpR, is crucially responsible for this osmotic regulation of the ompC and ompF genes. In this study, an E. coli gene was cloned, which interferes with expression of both the ompC and ompF genes at the level of transcription, provided that the cloned gene was introduced in E. coli cells by a multicopy plasmid. The gene product was identified as F107, which was previously characterized as a hypothetical protein in E. coli genome databases. F107 containing 107 amino acids appears to be highly hydrophobic, and has a sequence similarity to the eukaryotic type of cytochrome-c oxidase subunit III. The mechanism by which F107 inhibits transcription of ompC and ompF was examined extensively, mainly by using a set of envZ and ompR mutants. These results suggested that F107 interferes specifically with a function of the EnvZ osmosensory kinase. Possible mechanisms by which F107 affects the EnvZ function are discussed.
在大肠杆菌中，主要外膜蛋白OmpC和OmpF的表达会根据培养基渗透压及其他环境刺激进行调节。由EnvZ和OmpR介导的双组分信号转导系统对ompC和ompF基因的这种渗透调节起着关键作用。在本研究中，克隆了一个大肠杆菌基因，该基因在转录水平上干扰ompC和ompF基因的表达，前提是通过多拷贝质粒将克隆基因导入大肠杆菌细胞。该基因产物被鉴定为F107，它在大肠杆菌基因组数据库中先前被表征为一种假设蛋白。含有107个氨基酸的F107似乎高度疏水，并且与真核细胞型细胞色素c氧化酶亚基III具有序列相似性。主要通过使用一组envZ和ompR突变体，广泛研究了F107抑制ompC和ompF转录的机制。这些结果表明，F107特异性干扰EnvZ渗透感应激酶的功能。讨论了F107影响EnvZ功能的可能机制。
