论文部分内容阅读
GcvA蛋白是LysR转录因子家族成员,在大肠杆菌(Escherichia coli)中,它激活编码裂解甘氨酸酶系(GCV)操纵子(gcvTHP)的表达,这一过程受甘氨酸诱导.在以前的工作中,我们分别突变了苜蓿中华根瘤菌(Sinorhizobium meliloti)中90个LysR家族转录因子,并鉴定了突变株的表型.本研究证明了苜蓿中华根瘤菌基因组中存在2个gcvA基因gcvA1和gcvA2;苜蓿中华根瘤菌gcvTHP操纵子的充分激活需要它们的同时存在.gcvA1对gcvTHP操纵子的激活需要甘氨酸诱导,而gcvA2对gcvTHP操纵子的激活则不需要甘氨酸诱导,推测苜蓿中华根瘤菌中gcvTHP表达的调控机制与大肠杆菌中的不同.进化分析显示,很多原细菌中都存在GcvA蛋白,而苜蓿中华根瘤菌的GcvA1和GcvA2与大肠杆菌的GcvA的亲缘关系很远,这也许可以解释它们gcvTHP表达调控模式的不同.研究结果为LysR基因家族的功能提供了新的线索.
The GcvA protein is a member of the LysR transcription factor family and in Escherichia coli it activates the expression of the gene encoding the lytic glycine enzyme (GCV) operon (gcvTHP), a process induced by glycine. In previous work, we 90 LysR family transcription factors in Sinorhizobium meliloti were mutated respectively and their phenotypes were identified.The present study demonstrated that there are two gcvA genes gcvA1 and gcvA2 in S. meliloti genome, GcvTHP operon full activation requires their co-existence.GcvA1 gcvTHP operon activation requires glycine-induced gcvA2 gcvTHP operon activation is not required for glycine induction, speculated that S. meliloti gcvTHP expression in the regulatory mechanism and In E. coli, evolutionary analysis showed that GcvA protein was found in many of the original bacteria, whereas S. meliloti GcvA1 and GcvA2 were distantly related to E. coli GcvA, which may explain their different regulation patterns of gcvTHP expression The results provide new clues to the function of LysR gene family.