Backman K, Chen Y M, Magasanik B
Proc Natl Acad Sci U S A. 1981 Jun;78(6):3743-7. doi: 10.1073/pnas.78.6.3743.
We have cloned and characterized a fragment of the Escherichia coli chromosome spanning glnA, the structural gene for glutamine synthetase (L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2]. The fragment also carriers glnG, whose product is necessary for regulation of glnA expression, and a previously unidentified gene whose function we have not discovered. Transcription of glnA and the newly identified gene occurs divergently from a region between the two genes. Transcription of glnA proceeds toward glnG, which is transcribed in the same direction. A region of DNA between glnA and glnG contains genetic information whose loss may result in the inability to reduce expression of glnA and other operons in response to ammonia (the GlnC phenotype).
我们已经克隆并鉴定了一段大肠杆菌染色体片段，该片段跨越谷氨酰胺合成酶（L-谷氨酸：氨连接酶（ADP形成），EC 6.3.1.2）的结构基因glnA。该片段还携带glnG，其产物是调节glnA表达所必需的，以及一个我们尚未发现其功能的先前未鉴定基因。glnA和新鉴定基因的转录从这两个基因之间的一个区域向相反方向进行。glnA的转录朝着glnG进行，glnG以相同方向转录。glnA和glnG之间的一段DNA区域包含遗传信息，其缺失可能导致无法响应氨而降低glnA和其他操纵子的表达（GlnC表型）。
