Dataset Information

Characterization of myo-inositol utilization by Corynebacterium glutamicum: the stimulon, identification of transporters, and influence on L-lysine formation.

ABSTRACT: Although numerous bacteria possess genes annotated iol in their genomes, there have been very few studies on the possibly associated myo-inositol metabolism and its significance for the cell. We found that Corynebacterium glutamicum utilizes myo-inositol as a carbon and energy source, enabling proliferation with a high maximum rate of 0.35 h-1. Whole-genome DNA microarray analysis revealed that 31 genes respond to myo-inositol utilization, with 21 of them being localized in two clusters of >14 kb. A set of genomic mutations and functional studies yielded the result that some genes in the two clusters are redundant, and only cluster I is necessary for catabolizing the polyol. There are three genes which encode carriers belonging to the major facilitator superfamily and which exhibit a >12-fold increased mRNA level on myo-inositol. As revealed by mutant characterizations, one carrier is not involved in myo-inositol uptake whereas the other two are active and can completely replace each other with apparent Kms for myo-inositol as a substrate of 0.20 mM and 0.45 mM, respectively. Interestingly, upon utilization of myo-inositol, the L-lysine yield is 0.10 mol/mol, as opposed to 0.30 mol/mol, with glucose as the substrate. This is probably not only due to myo-inositol metabolism alone since a mixture of 187 mM glucose and 17 mM myo-inositol, where the polyol only contributes 8% of the total carbon, reduced the L-lysine yield by 29%. Moreover, genome comparisons with other bacteria highlight the core genes required for growth on myo-inositol, whose metabolism is still weakly defined.

SUBMITTER: Krings E

PROVIDER: S-EPMC1698185 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature

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Characterization of myo-inositol utilization by Corynebacterium glutamicum: the stimulon, identification of transporters, and influence on L-lysine formation.

Krings Eva E Krumbach Karin K Bathe Brigitte B Kelle Ralf R Wendisch Volker F VF Sahm Hermann H Eggeling Lothar L

Journal of bacteriology 20060922 23

Although numerous bacteria possess genes annotated iol in their genomes, there have been very few studies on the possibly associated myo-inositol metabolism and its significance for the cell. We found that Corynebacterium glutamicum utilizes myo-inositol as a carbon and energy source, enabling proliferation with a high maximum rate of 0.35 h-1. Whole-genome DNA microarray analysis revealed that 31 genes respond to myo-inositol utilization, with 21 of them being localized in two clusters of >14 k ...[more]

PMID: 16997948

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Project description: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.

Dataset Information

Characterization of myo-inositol utilization by Corynebacterium glutamicum: the stimulon, identification of transporters, and influence on L-lysine formation.

Publications

Characterization of myo-inositol utilization by Corynebacterium glutamicum: the stimulon, identification of transporters, and influence on L-lysine formation.

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