Belitsky B R, Wray L V, Fisher S H, Bohannon D E, Sonenshein A L
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
J Bacteriol. 2000 Nov;182(21):5939-47. doi: 10.1128/JB.182.21.5939-5947.2000.
Synthesis of glutamate, the cell's major donor of nitrogen groups and principal anion, occupies a significant fraction of bacterial metabolism. In Bacillus subtilis, the gltAB operon, encoding glutamate synthase, requires a specific positive regulator, GltC, for its expression. In addition, the gltAB operon was shown to be repressed by TnrA, a regulator of several other genes of nitrogen metabolism and active under conditions of ammonium (nitrogen) limitation. TnrA was found to bind directly to a site immediately downstream of the gltAB promoter. As is true for other genes, the activity of TnrA at the gltAB promoter was antagonized by glutamine synthetase under certain growth conditions.
谷氨酸是细胞氮基团的主要供体和主要阴离子，其合成在细菌代谢中占很大一部分。在枯草芽孢杆菌中，编码谷氨酸合酶的gltAB操纵子需要一种特定的正调控因子GltC来进行表达。此外，gltAB操纵子被证明受到TnrA的抑制，TnrA是氮代谢其他几个基因的调控因子，在铵（氮）限制条件下具有活性。发现TnrA直接结合到gltAB启动子下游紧邻的一个位点。与其他基因一样，在某些生长条件下，谷氨酰胺合成酶会拮抗TnrA在gltAB启动子处的活性。
