PMID:14731280
| Citation |
Metzner, M, Germer, J and Hengge, R (2004) Multiple stress signal integration in the regulation of the complex sigma S-dependent csiD-ygaF-gabDTP operon in Escherichia coli. Mol. Microbiol. 51:799-811 |
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| Abstract |
The csiD-ygaF-gabDTP region in the Escherichia coli genome represents a cluster of sigma S-controlled genes. Here, we investigated promoter structures, sigma factor dependencies, potential co-regulation and environmental regulatory patterns for all of these genes. We find that this region constitutes a complex operon with expression being controlled by three differentially regulated promoters: (i) csiDp, which affects the expression of all five genes, is cAMP-CRP/sigma S-dependent and activated exclusively upon carbon starvation and stationary phase; (ii) gabDp1, which is sigma S-dependent and exhibits multiple stress induction like sigma S itself; and (iii) gabDp2[previously suggested by Schneider, B.L., Ruback, S., Kiupakis, A.K., Kasbarian, H., Pybus, C., and Reitzer, L. (2002) J. Bacteriol. 184: 6976-6986], which appears to be Nac/sigma 70-controlled and to respond to poor nitrogen sources. In addition, we identify a novel repressor, CsiR, which modulates csiDp activity in a temporal manner during early stationary phase. Finally, we propose a physiological role for sigma S-controlled GabT/D-mediated gamma-aminobutyrate (GABA) catabolism and glutamate accumulation in general stress adaptation. This physiological role is reflected by the activation of the operon-internal gabDp1 promoter under the different conditions that also induce sigma S, which include shifts to acidic pH or high osmolarity as well as starvation or stationary phase. |
| Links | |
| Keywords |
Bacterial Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial; Genes, Reporter; Glutamic Acid/metabolism; Operon; Promoter Regions, Genetic; Repressor Proteins/metabolism; Sigma Factor/metabolism; Signal Transduction/physiology; gamma-Aminobutyric Acid/metabolism |
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