Molecular characterization of the mycobacterial SenX3-RegX3 two-component system: evidence for autoregulation.
Environmental regulation of bacterial gene expression is often mediated by two-component signal transduction systems, which are themselves tightly regulated. The response regulator RegX3 and the cytoplasmic portion of the histidine kinase SenX3 from Mycobacterium bovis BCG were overproduced in Escherichia coli and purified as N-terminally (His)(6)-tagged proteins. Phosphorylation assays demonstrated autophosphorylation of the cytoplasmic portion of SenX3 and a phosphotransfer from SenX3 to RegX3, involving conserved histidine and aspartate residues, respectively. In addition, as shown by electrophoretic mobility shift assays, (His)(6)RegX3 was able to specifically bind to the promoter region of the senX3-regX3 operon. Furthermore, operon fusion analyses indicated that the overexpression of the senX3-regX3 operon increases the activity of the senX3 promoter in Mycobacterium smegmatis. Together, these results indicate that the mycobacterial SenX3-RegX3 two-component system is positively autoregulated.
Himpens
Sabine
S
INSERM U447, Institut Pasteur de Lille/Institut de Biologie de Lille, 1 rue du Professeur Calmette, F-59019 Lille Cedex, France1.
Locht
Camille
C
INSERM U447, Institut Pasteur de Lille/Institut de Biologie de Lille, 1 rue du Professeur Calmette, F-59019 Lille Cedex, France1.
Supply
Philip
P
INSERM U447, Institut Pasteur de Lille/Institut de Biologie de Lille, 1 rue du Professeur Calmette, F-59019 Lille Cedex, France1.
D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine / Q000737:chemistry; D006706:Homeostasis; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000235:genetics* / Q000378:metabolism; D009876:Operon; D010766:Phosphorylation; D010770:Phosphotransferases; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D001426:Bacterial Proteins; D011994:Recombinant Proteins; C110608:RegX3 protein, Mycobacterium; D006639:Histidine; D010770:Phosphotransferases; C110607:SenX3 protein, Mycobacterium