LrhA as a new transcriptional key regulator of flagella, motility and chemotaxis genes in Escherichia coli
LrhA as a new transcriptional key regulator of flagella, motility and chemotaxis genes in Escherichia coli
复制标题
DOI：
10.1046/j.1365-2958.2002.03032.x
复制
发表时间：
2002-07-01
影响因子：
3.6
通讯作者：
Unden, G
中科院分区：
文献类型：
--
作者：
Lehnen, D;Blumer, C;Unden, G
大肠杆菌LysR型调节因子LrhA的功能是通过比较野生型大肠杆菌的全基因组mRNA谱来确定的。大肠杆菌和同基因lrhA突变体的DNA微阵列。在lrhA突变体中，大量（48）的基因参与鞭毛，运动和趋化性表现出相对mRNA丰度增加3和80之间的因素。当一组有代表性的5鞭毛，运动性和趋化性基因进行了测试，在lacZ报告基因融合，类似的因素去阻遏中发现lrhA突变体。在凝胶阻滞实验中，LrhA蛋白特异性结合flhD和lrhA启动子DNA（表观K-D约为20 nM），而fliC、fliA和trg的启动子不被LrhA结合。在lrhA突变体中，flhDC（编码FlhD（2）C（2））的表达被去抑制3.5倍。FlhD（2）C（2）是鞭毛和趋化基因表达的主要调节因子。通过DNA酶I足迹法，鉴定了flhDC和lrhA启动子处的LrhA结合位点。凝胶阻滞和lrhA表达研究表明，lrhA基因是在LrhA的正性自身调节下。这表明LrhA通过调节FlhD（2）C（2）的合成和浓度来控制鞭毛、运动和趋化基因的转录。
The function of the LysR-type regulator LrhA of Escherichia coli was defined by comparing whole-genome mRNA profiles from wild-type E. coli and an isogenic lrhA mutant on a DNA microarray. In the lrhA mutant, a large number (48) of genes involved in flagellation, motility and chemotaxis showed relative mRNA abundances increased by factors between 3 and 80. When a representative set of five flagellar, motility and chemotaxis genes was tested in lacZ reporter gene fusions, similar factors for derepression were found in the lrhA mutant. In gel retardation experiments, the LrhA protein bound specifically to flhD and lrhA promoter DNA (apparent K-D approximate to 20 nM), whereas the promoters of fliC , fliA and trg were not bound by LrhA. The expression of flhDC (encoding FlhD(2)C(2)) was derepressed by a factor of 3.5 in the lrhA mutant. FlhD(2)C(2) is known as the master regulator for the expression of flagellar and chemotaxis genes. By DNase I footprinting, LrhA binding sites at the flhDC and lrhA promoters were identified. The lrhA gene was under positive autoregulation by LrhA as shown by gel retardation and lrhA expression studies. It is suggested that LrhA is a key regulator controlling the transcription of flagellar, motility and chemotaxis genes by regulating the synthesis and concentration of FlhD(2)C(2).