Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Complex regulation of the PEP carboxykinase gene pck and characterization of its GntR-type regulator IolR as a repressor of myo-inositol utilization genes in Corynebacterium glutamicum

ABSTRACT: DNA affinity chromatography with the promoter region of the Corynebacterium glutamicum pck gene, encoding phosphoenolpyruvate carboxykinase (PEPCk), led to the isolation of four transcriptional regulators, i.e., RamA, GntR1, GntR2 and IolR. Determination of the PEPCk activity of the deletion mutants M-NM-^TramA, M-NM-^TgntR1M-NM-^TgntR2, and M-NM-^TiolR indicated that RamA represses pck during growth on glucose about twofold, whereas GntR1, GntR2, and IolR activate pck expression about twofold, irrespective whether glucose or acetate served as carbon source. The DNA binding sites of the four regulators in the pck promoter region were identified and their positions correlated with the predicted functions as repressor or activators. The iolR gene is located upstream and in divergent orientation to a iol gene cluster, encoding proteins involved in myo-inositol uptake and degradation. Comparative DNA microarray analysis of the M-NM-^TiolR mutant and the parental wild-type revealed strongly elevated (>100-fold) mRNA levels of the iol genes in the mutant, indicating that the primary function of IolR is the repression of the iol genes. IolR binding sites were identified in the promoter regions of iolC, iolT and iolR itself, which presumably is subject to negative autoregulation. A consensus DNA-binding motif was identified (5M-bM-^@M-^Y-KGWCHTRACA-3M-bM-^@M-^Y) which corresponds well to those of other GntR-type regulators of the HutC family. Taken together, our results disclose a complex regulation of the pck gene in C. glutamicum and identify IolR as an efficient repressor of genes involved in myo-inositol catabolism of this organism. To identify genes that are potentially regulated by IolR, the transcriptome profile of the iolR deletion strain was compared to that of the WT using DNA microarray analysis. The strains were grown in CGXII minimal medium with 4% (wt/vol) glucose as sole carbon source and RNA was isolated from cells harvested in the early exponential growth phase (OD600 of about 5). The transcriptome comparison was performed in triplicate starting from independent cultures. The second replicate included a dye-swap.

ORGANISM(S): Corynebacterium glutamicum ATCC 13032

SUBMITTER: Tino Polen

PROVIDER: E-GEOD-44812 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Complex regulation of the phosphoenolpyruvate carboxykinase gene pck and characterization of its GntR-type regulator IolR as a repressor of myo-inositol utilization genes in Corynebacterium glutamicum.

Klaffl Simon S Brocker Melanie M Kalinowski Jörn J Eikmanns Bernhard J BJ Bott Michael M

Journal of bacteriology 20130719 18

DNA affinity chromatography with the promoter region of the Corynebacterium glutamicum pck gene, encoding phosphoenolpyruvate carboxykinase, led to the isolation of four transcriptional regulators, i.e., RamA, GntR1, GntR2, and IolR. Determination of the phosphoenolpyruvate carboxykinase activity of the ΔramA, ΔgntR1 ΔgntR2, and ΔiolR deletion mutants indicated that RamA represses pck during growth on glucose about 2-fold, whereas GntR1, GntR2, and IolR activate pck expression about 2-fold irres ...[more]

PMID: 23873914

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Dataset Information

Complex regulation of the PEP carboxykinase gene pck and characterization of its GntR-type regulator IolR as a repressor of myo-inositol utilization genes in Corynebacterium glutamicum

Publications

Complex regulation of the phosphoenolpyruvate carboxykinase gene pck and characterization of its GntR-type regulator IolR as a repressor of myo-inositol utilization genes in Corynebacterium glutamicum.

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