ISOLATION AND CHARACTERIZATION OF DELETION MUTANTS OF OMPR AND ENVZ, REGULATORY GENES FOR EXPRESSION OF THE OUTER-MEMBRANE PROTEINS OMPC AND OMPF IN ESCHERICHIA-COLI
ISOLATION AND CHARACTERIZATION OF DELETION MUTANTS OF OMPR AND ENVZ, REGULATORY GENES FOR EXPRESSION OF THE OUTER-MEMBRANE PROTEINS OMPC AND OMPF IN ESCHERICHIA-COLI
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DOI：
10.1093/oxfordjournals.jbchem.a121923
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发表时间：
1987-02-01
影响因子：
2.7
通讯作者：
MIZUSHIMA, S
中科院分区：
文献类型：
--
作者：
MIZUNO, T;MIZUSHIMA, S
已知分别编码主要外膜蛋白OmpC和OmpF的ompC和ompF基因的表达受至少两种调节基因ompR和envZ控制，所述两种调节基因一起构成单个ompB操纵子。我们构建了ompR-envZ缺失或envZ缺失的染色体突变体。这些缺失或菌株的表征表明，OmpR蛋白是ompC和ompF基因转录所必需的，并且EnvZ蛋白是ompC和ompF表达的正常调节所必需的，其受介质渗透压的影响。我们还构建了携带ompB操纵子的不同部分的几种质粒。这些质粒的表征使我们能够鉴定出表观分子量为29千道尔顿（kDa）的OmpR蛋白和表观分子量为50 kDa的EnvZ蛋白。EnvZ翻译的起始密码子似乎与OmpR翻译的终止密码子重叠。还发现缺少N-末端55个氨基酸残基的截短的EnvZ多肽（44 kDa）可以补充envZ缺失突变体。基于这些结果，ompB操纵子的结构和功能的ompC和ompF表达的调控进行了讨论。
Expression of the ompC and ompF genes coding for the major outer membrane proteins, OmpC and OmpF, respectively, is known to be controlled by at least two regulatory genes, ompR and envZ, which together comprise a single ompB operon. We constructed chromosomal mutants with either ompR-envZ deletion or envZ deletion. Characterization of these deletion or strains showed that the OmpR protein is necessary for transcription of the ompC and ompF genes, and the EnvZ protein is essential for normal regulation of the ompC and ompF expression, which is affected by the medium osmolarity. We also constructed several plasmids carrying different portions of the ompB operon. Characterization of these plasmids allowed us to identify the OmpR protein with an apparent molecular weight of 29 kilodaltons (kDa) and the EnvZ protein with an apparent molecular weight of 50 kDa. The initiation codon for EnvZ translation appeared to overlap with the termination codon for OmpR translation. It was also found that a truncated EnvZ polypeptide (44 kDa) which lacks the N-terminal 55 amino acid residues can complement the envZ deletion mutant. Based on these results, the structure and function of the ompB operon are discussed in relation to the regulation of ompC and ompF expression.