Acid stress response in Escherichia coli: mechanism of regulation of gadA transcription by RcsB and GadE.
Escherichia coli can survive extreme acid stress for several hours. The most efficient acid resistance system is based on glutamate decarboxylation by the GadA and GadB decarboxylases and the import of glutamate via the GadC membrane protein. The expression of the corresponding genes is controlled by GadE, the central activator of glutamate-dependent acid resistance (GDAR). We have previously shown by genetic approaches that as well as GadE, the response regulator of the Rcs system, RcsB is absolutely required for control of gadA/BC transcription. In the presence of GadE, basal activity of RcsB stimulates the expression of gadA/BC, whereas activation of RcsB leads to general repression of the gad genes. We report here the results of various in vitro assays that show RcsB to regulate by direct binding to the gadA promoter region. Furthermore, activation of gadA transcription requires a GAD box and binding of an RcsB/GadE heterodimer. In addition, we have identified an RcsB box, which lies just upstream of the -10 element of gadA promoter and is involved in repression of this operon.
Castanié-Cornet
Marie-Pierre
MP
Université de Toulouse, UPS, Laboratoire de Microbiologie et Génétique Moléculaires, F-31000 Toulouse and CNRS, LMGM, F-31000 Toulouse, France. castanie@ibcg.biotoul.fr
Cam
Kaymeuang
K
Bastiat
Bénédicte
B
Cros
Adeline
A
Bordes
Patricia
P
Gutierrez
Claude
C
D001665:Binding Sites; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005968:Glutamate Decarboxylase / Q000096:biosynthesis / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D017354:Point Mutation; D050436:Regulatory Elements, Transcriptional; D013312:Stress, Physiological / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D029968:Escherichia coli Proteins; C479562:GadE protein, E coli; D008565:Membrane Proteins; C489568:RcsB protein, E coli; D014157:Transcription Factors; C121044:gadA protein, E coli; D005968:Glutamate Decarboxylase