Involvement of Nitrogen Regulation in Bacillus subtilis degU Expression
Involvement of Nitrogen Regulation in Bacillus subtilis degU Expression
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DOI：
10.1128/jb.00368-08
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发表时间：
2008-05
影响因子：
3.2
通讯作者：
Ayako Yasumura;Sadanobu Abe;Teruo Tanaka
中科院分区：
文献类型：
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作者：
Ayako Yasumura;Sadanobu Abe;Teruo Tanaka
摘要枯草芽孢杆菌DegS-DegU属于细菌双组分系统，控制着胞外蛋白酶的产生和感受态的发育。发现当破坏参与氮调节的谷氨酰胺合成酶基因glnA时，应答调节因子degU基因的表达增加。缺失分析和5′-末端定位结果表明，degU基因前的启动子P2的诱导作用导致了degU基因表达量的增加。破坏tnrA，氮调节的全球调节器，消除了P2启动子诱导的glnA突变。P2启动子受氮调节的事实通过P2表达随氮限制生长的增加而证明。通过引物延伸分析还发现，degU由位于P2下游的另一个启动子P3转录。P3的有效表达依赖于磷酸化的DegU，因为传感器激酶基因degS的失活导致degU表达的丧失，尽管在degS缺陷突变体中也观察到degU水平提高的情况下degU表达的有效刺激降低。位于degSU操纵子上游的启动子，在此称为P1启动子，对glnA和degU突变不敏感。这些结果表明，在不同的生长条件下，degU的表达是由三个启动子控制。
ABSTRACT Bacillus subtilis DegS-DegU belongs to a bacterial two-component system that controls many processes, including the production of exocellular proteases and competence development. It was found that when the glutamine synthetase gene glnA, which is involved in nitrogen regulation, was disrupted, the expression of the response regulator degU gene was increased. Deletion analysis and 5′-end mapping of the degU transcripts showed that the increase was caused by induction of a promoter (P2) located before the degU gene. Disruption of tnrA, a global regulator of nitrogen regulation, eliminated the P2 promoter induction by the glnA mutation. The fact that the P2 promoter is under nitrogen regulation was demonstrated by an increase in P2 expression with nitrogen-limited growth. It was also found by primer extension analysis that degU was transcribed by another promoter, P3, that is located downstream of P2. Efficient expression of P3 was dependent on phosphorylated DegU, as inactivation of the sensor kinase gene, degS, resulted in the loss of degU expression, although less efficient stimulation of degU expression was also observed with an enhanced level of DegU in a degS-deficient mutant. The promoter located upstream of the degSU operon, designated the P1 promoter here, was insensitive to glnA and degU mutations. These results suggest that degU expression is controlled by the three promoters under different growth conditions.