大肠杆菌中甲硫氨酸合成的调控：metJ基因产物和S-腺苷甲硫氨酸对metB、metL和metJ基因体外表达的影响。

Regulation of methionine synthesis in Escherichia coli: effect of metJ gene product and S-adenosylmethionine on the in vitro expression of the metB, metL and metJ genes.

作者信息

Shoeman R, Coleman T, Redfield B, Greene R C, Smith A A, Saint-Girons I, Brot N, Weissbach H

出版信息

Biochem Biophys Res Commun. 1985 Dec 17;133(2):731-9. doi: 10.1016/0006-291x(85)90965-9.

Abstract

The regulation of the expression of three Escherichia coli met genes, metB, which codes for cystathionine gamma-synthetase (EC 4.2.99.9), metL, which codes for aspartokinase II-homoserine dehydrogenase II (EC 2.7.2.4-EC 1.1.1.3) and metJ, which codes for the methionine regulon aporepressor, has been studied using highly purified DNA-directed in vitro protein synthesis systems. In a system where the entire gene product is synthesized, the expression of the metB and metL genes is specifically inhibited by MetJ protein (repressor protein) and S-adenosylmethionine (AdoMet). In a simplified system that measures the formation of the first dipeptide of the gene product (fMet-Ala for the metJ gene), MetJ protein and AdoMet partially repress (approximately 40-60%) metJ gene expression. Thus, the metJ gene can be partially autoregulated by its gene product.

摘要

利用高度纯化的DNA指导的体外蛋白质合成系统，对三种大肠杆菌met基因（即编码胱硫醚γ-合成酶（EC 4.2.99.9）的metB、编码天冬氨酸激酶II-高丝氨酸脱氢酶II（EC 2.7.2.4-EC 1.1.1.3）的metL以及编码甲硫氨酸调节子无辅基阻遏物的metJ）的表达调控进行了研究。在一个合成整个基因产物的系统中，metB和metL基因的表达受到MetJ蛋白（阻遏蛋白）和S-腺苷甲硫氨酸（AdoMet）的特异性抑制。在一个测量基因产物第一个二肽（metJ基因的fMet-Ala）形成的简化系统中，MetJ蛋白和AdoMet部分抑制（约40%-60%）metJ基因的表达。因此，metJ基因可被其基因产物部分自动调节。