CHARACTERIZATION OF THE ESCHERICHIA-COLI GCVR GENE ENCODING A NEGATIVE REGULATOR OF GCV EXPRESSION
CHARACTERIZATION OF THE ESCHERICHIA-COLI GCVR GENE ENCODING A NEGATIVE REGULATOR OF GCV EXPRESSION
复制标题
DOI：
10.1128/jb.177.17.4980-4984.1995
复制
发表时间：
1995-09-01
影响因子：
3.2
通讯作者：
STAUFFER, GV
中科院分区：
文献类型：
--
作者：
GHRIST, AC;STAUFFER, GV
大肠杆菌甘氨酸裂解酶系统催化甘氨酸的裂解，产生CO2、NH3和一个碳单元。编码这种酶系统（gcv）的操纵子的表达在甘氨酸存在下被诱导，在嘌呤存在下被抑制。在这项研究中，一个高水平的组成型表达的gcvT-lacZ基因融合的突变体被分离出来。该菌株中的突变被命名为gcvR 1，并在E. coli染色体。携带野生型gcvR基因的单拷贝质粒补充了突变，恢复了gcvT-lacZ融合的正常调节，而携带gcvR的多拷贝质粒导致在所有生长条件下的超抑制。GcvR对gcvT-lacZ融合的负调节显示需要GcvA，GcvA是已知在甘氨酸存在下激活gcv和在嘌呤存在下抑制gcv的LysR家族蛋白。模型解释如何GcvR和GcvA可能相互作用，以调节gcv的表达。
The Escherichia coli glycine cleavage enzyme system catalyzes the cleavage of glycine, generating CO2, NH3, and a one-carbon unit. Expression of the operon encoding this enzyme system (gcv) is induced in the presence of glycine and repressed in the presence of purines. In this study, a mutant with high-level constitutive expression of a gcvT-lacZ gene fusion was isolated. The mutation in this strain was designated gcvR1 and was mapped to min 53.3 on the E. coli chromosome. A single-copy plasmid carrying the wild-type gcvR gene complemented the mutation, restoring normal regulation of a gcvT-lacZ fusion, while a multicopy plasmid carrying gcvR led to superrepression under all growth conditions. Negative regulation of a gcvT-lacZ fusion by GcvR was shown to require GcvA, a LysR family protein known to both activate gcv in the presence of glycine and repress gcv in the presence of purines. Models explaining how GcvR and GcvA might interact to regulate gcv expression are proposed.