Target Genes, Consensus Binding Site, and Role of Phosphorylation for the Response Regulator MtrA of Corynebacterium glutamicum
Target Genes, Consensus Binding Site, and Role of Phosphorylation for the Response Regulator MtrA of Corynebacterium glutamicum
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DOI：
10.1128/jb.01032-10
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发表时间：
2011-03-01
影响因子：
3.2
通讯作者：
Bott, Michael
中科院分区：
文献类型：
--
作者：
Brocker, Melanie;Mack, Christina;Bott, Michael
由传感激酶MtrB和反应调节剂MtrA组成的双组分信号转导系统在棒状杆菌和分枝杆菌中高度保守。尽管结核分枝杆菌的mtrA被报道是必不可少的，我们最近成功地创建了谷氨酸棒杆菌的Delta mtrAB和Delta mtrA缺失突变体，并提供了mepA和nlpC（两者都编码推定的细胞壁肽酶）被MtrA直接抑制的证据，而proP和betP（两者都编码相容溶质的载体）被MtrA直接激活。在本研究中，新的MtrA靶基因被确定，包括mepB，编码另一个假定的细胞壁肽酶。MtrA的阻遏物或激活物功能与MtrA结合位点和转录起始位点之间的距离相关。从20个靶启动子内鉴定的结合位点，衍生出19-bp的MtrA共有基序，其代表由3个碱基对分隔的8个碱基对的直接重复。含有具有D53 N突变的MtrA而不是野生型MtrA的菌株的基因表达类似于Delta mtrA突变体的基因表达，这表明MtrA以其磷酸化形式具有活性。该结果通过使用磷酸化的MtrA的电泳迁移率变动测定得到证实，磷酸化的MtrA显示出增加的结合亲和力。
The two-component signal transduction system consisting of the sensor kinase MtrB and the response regulator MtrA is highly conserved in corynebacteria and mycobacteria. Whereas mtrA of Mycobacterium tuberculosis was reported to be essential, we recently succeeded in creating Delta mtrAB and Delta mtrA deletion mutants of Corynebacterium glutamicum and provided evidence that mepA and nlpC, both encoding putative cell wall peptidases, are directly repressed by MtrA, whereas proP and betP, both encoding carriers for compatible solutes, are directly activated by MtrA. In the present study, novel MtrA target genes were identified, including mepB, encoding another putative cell wall peptidase. The repressor or activator functions of MtrA correlate with the distance between the MtrA binding site and the transcriptional start site. From the identified binding sites within 20 target promoters, a 19-bp MtrA consensus motif was derived which represents a direct repeat of 8 base pairs separated by 3 base pairs. Gene expression of a strain containing MtrA with a D53N mutation instead of wild-type MtrA resembled that of a Delta mtrA mutant, indicating that MtrA is active in its phosphorylated form. This result was confirmed by electrophoretic mobility shift assays with phosphorylated MtrA which showed an increased binding affinity.