Streicher S L, Bender R A, Magasanik B
J Bacteriol. 1975 Jan;121(1):320-31. doi: 10.1128/jb.121.1.320-331.1975.
Mutations at two sites, glnA and glnB, of the Klebsiella aerogenes chromosome result in the loss of glutamine synthetase. The locations of these sites on the chromosome were established by complementation by episomes of Escherichia coli and by determination of their linkage to other genetic sites by transduction with phage P1. The glnB gene is located at a position corresponding to 48 min on the Taylor map of the E. coli chromosome; it is linked to tryA, nadB, and GUA. The glnA gene is at a position corresponding to 77 min on the Taylor map and is linked to rha and metB; it is also closely linked to rbs, located in E. coli at 74 min, indicating a difference in this chromosomal region between E. coli and K. aerogenes. Mutations in the glnA site can also lead to nonrepressible synthesis of active glutamine synthetase. The examination of the fine genetic structure of glnA revealed that one such mutation is located between two mutations leading to the loss of enzymatic activity. This result, together with evidence that the structural gene for glutamine synthetase is at glnA, suggests that glutamine synthetase controls expression of its own structural gene by repression.
产气克雷伯氏菌染色体上谷氨酰胺合成酶基因（glnA）和glnB两个位点的突变会导致谷氨酰胺合成酶缺失。通过大肠杆菌附加体的互补作用以及利用噬菌体P1转导确定它们与其他基因位点的连锁关系，确定了这些位点在染色体上的位置。glnB基因位于大肠杆菌染色体泰勒图谱上对应于48分钟的位置；它与tryA、nadB和GUA连锁。glnA基因位于泰勒图谱上对应于77分钟的位置，与rha和metB连锁；它还与位于大肠杆菌74分钟处的rbs紧密连锁，这表明大肠杆菌和产气克雷伯氏菌在这个染色体区域存在差异。glnA位点的突变也可导致活性谷氨酰胺合成酶的不可阻遏合成。对glnA精细遗传结构的研究表明，其中一个这样的突变位于导致酶活性丧失的两个突变之间。这一结果，连同谷氨酰胺合成酶的结构基因位于glnA的证据，表明谷氨酰胺合成酶通过阻遏作用控制其自身结构基因的表达。
