PMID:22101843
| Citation |
Scheu, PD, Witan, J, Rauschmeier, M, Graf, S, Liao, YF, Ebert-Jung, A, Basché, T, Erker, W and Unden, G (2012) CitA/CitB two-component system regulating citrate fermentation in Escherichia coli and its relation to the DcuS/DcuR system in vivo. J. Bacteriol. 194:636-45 |
|---|---|
| Abstract |
Citrate fermentation by Escherichia coli requires the function of the citrate/succinate antiporter CitT (citT gene) and of citrate lyase (citCDEFXG genes). Earlier experiments suggested that the two-component system CitA/CitB, consisting of the membrane-bound sensor kinase CitA and the response regulator CitB, stimulates the expression of the genes in the presence of citrate, similarly to CitA/CitB of Klebsiella pneumoniae. In this study, the expression of a chromosomal citC-lacZ gene fusion was shown to depend on CitA/CitB and citrate. CitA/CitB is related to the DcuS/DcuR two-component system which induces the expression of genes for fumarate respiration in response to C(4)-dicarboxylates and citrate. Unlike DcuS, CitA required none of the cognate transporters (CitT, DcuB, or DcuC) for function, and the deletion of the corresponding genes showed no effect on the expression of citC-lacZ. The citAB operon is preceded by a DcuR binding site. Phosphorylated DcuR bound specifically to the promoter region, and the deletion of dcuS or dcuR reduced the expression of citC. The data indicate the presence of a regulatory cascade consisting of DcuS/DcuR modulating citAB expression (and CitA/CitB levels) and CitA/CitB controlling the expression of the citCDEFXGT gene cluster in response to citrate. In vivo fluorescence resonance energy transfer (FRET) and the bacterial two-hybrid system (BACTH) showed interaction between the DcuS and CitA proteins. However, BACTH and expression studies demonstrated the lack of interaction and cross-regulation between CitA and DcuR or DcuS and CitB. Therefore, there is only linear phosphoryl transfer (DcuS→DcuR and CitA→CitB) without cross-regulation between DcuS/DcuR and CitA/CitB. |
| Links |
PubMed PMC3264064 Online version:10.1128/JB.06345-11 |
| Keywords |
Citric Acid/metabolism; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Fermentation; Gene Expression Regulation, Bacterial; Promoter Regions, Genetic; Protein Binding; Protein Kinases/genetics; Protein Kinases/metabolism; Transcription Factors/genetics; Transcription Factors/metabolism |
| edit table |
Significance
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
Annotations
<annotationlinks/>
EcoliWiki Links
Add links to pages that link here (e.g. gene, product, method pages)
See also
References
See Help:References for how to manage references in EcoliWiki.