MECHANISM OF SYNTHESIS OF SECRETORY PROTEIN AND ITS GENE EXPRESSION IN ESCHERICHIA CORI

研究了编码主要外膜蛋白OmpC和OmpF的基因的表达机制。在这一调控机制的研究中，获得了许多重要的结果和启示。ompC和ompF基因的缺失以及碱基取代分析揭示，ompC和ompF启动子完全发挥功能需要从各自的典型启动子（-35，-10区域）上游延伸的60至70个碱基对序列，并且OmpR蛋白最可能通过结合ompC和ompF启动子的上游区域来激活这些基因的表达。已经克隆了几个突变ompR基因以及野生型ompR基因，并且已经确定了核苷酸序列。事实上，不同的ompR基因上的突变位点的不同的α-调节谱强烈支持的观点，即OmpR蛋白直接参与α-调节，这种蛋白质需要一个多聚体结构作为一个功能单元。envZ缺失突变体的分离显示，EnvZ蛋白似乎不仅在ompC和ompF基因的完全表达中起重要作用，而且在取决于介质渗透压的表达波动中也起重要作用。将OmpR蛋白纯化至均一并表征。此外，证明了OmpR蛋白与ompC和ompF基因的启动子区的直接结合。

Mechanism of the expression of the genes coding for major outer membrane protein, OmpC and OmpF, has been studied. Many important results and implications about the morecular mechanism of the regulation have been obtained. Deletion as well as base substitution analysis of the ompC and ompF genes revealed that 60 to 70 base pair sequences extending upstream from the respective canonical promoters (-35,-10 regions) are required for the ompC and ompF promoters to function fully, and that OmpR protein activates the expression of these genes most likely by binding to the upstream regions of the ompC and ompF promoters. Several mutant ompR genes as well as the wild-type ompR gene have been cloned, and the nucleotide sequences have been determined. The fact that the osmoregulatory profiles differed depending on the site of mutation on the ompR gene strongly supported the view that OmpR protein is directly involved in osmoregulation, and that this protein takes a multimeric structure as a functional unit. Isolation of an envZ deletion mutant revealed that EnvZ protein appeared to play an important role not only in the full expression of the ompC and ompF genes, but also in the fluctuation of the expression depending on the medium osmolarity. OmpR protein was purified to homogeneity and characterized. Furthermore, direct binding of OmpR protein to the promoter regions of the ompC and ompF genes was demonstrated.