The GlxR regulon of the amino acid producer Corynebacterium glutamicum: Detection of the corynebacterial core regulon and integration into the transcriptional regulatory network model

Kohl, Thomas A.; Tauch, Andreas

doi:10.1016/j.jbiotec.2009.08.005

Cited by 64 publications

(107 citation statements)

References 47 publications

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“…The GlxR protein was initially characterized as a transcriptional regulator that represses the aceB gene of the glyoxylate bypass (65). Additional studies showed that GlxR is a global regulator with dual functionality that is predicted to directly regulate about 14% of the annotated C. glutamicum genes (66)(67)(68)(69). Binding of GlxR to several of its target promoters was shown to be strictly dependent on the presence of cAMP in vitro (40,41,65,68,(70)(71)(72)(73).…”

Section: Discussionmentioning

confidence: 99%

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

Klaffl¹,

Brocker²,

Kalinowski³

et al. 2013

Journal of Bacteriology

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c 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 ⌬ramA, ⌬gntR1 ⌬gntR2, and ⌬iolR 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 irrespective of whether glucose or acetate served as the 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 a divergent orientation with respect to a iol gene cluster, encoding proteins involved in myoinositol uptake and degradation. Comparative DNA microarray analysis of the ⌬iolR mutant and the parental wild-type strain revealed strongly (>100-fold) elevated 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, iolT1, and iolR. IolR therefore is presumably subject to negative autoregulation. A consensus DNA binding motif (5=-KGWCHTRACA-3=) which corresponds well to those of other GntR-type regulators of the HutC family was identified. 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.

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Section: Discussionmentioning

confidence: 99%

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

Klaffl¹,

Brocker²,

Kalinowski³

et al. 2013

Journal of Bacteriology

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“…During our work on the systematic reconstruction of the transcriptional regulatory network in the Gram-positive model organism Corynebacterium glutamicum Kohl & Tauch, 2009), we recognized the Cg0897 (PdxR) protein as a candidate to control the expression of the pdxST genes in this species. According to genome annotation data, the Cg0897 protein was grouped into the GntR family of DNA-binding transcription regulators (Brune et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Positive transcriptional control of the pyridoxal phosphate biosynthesis genes pdxST by the MocR-type regulator PdxR of Corynebacterium glutamicum ATCC 13032

2011

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The pdxR (cg0897) gene of Corynebacterium glutamicum ATCC 13032 encodes a regulatory protein belonging to the MocR subfamily of GntR-type transcription regulators and consisting of an amino-terminal winged helix-turn-helix DNA-binding domain and a carboxy-terminal aminotransferase-like domain. A defined deletion in the pdxR gene resulted in the decreased expression of the divergently orientated pdxST genes coding for the subunits of pyridoxal 59-phosphate synthase. The pdxST mutant C. glutamicum NJ0898 and the pdxR mutant C. glutamicum AMH17 showed vitamin B 6 auxotrophy that was restored by supplementing the growth medium with either pyridoxal, pyridoxal 59-phosphate or pyridoxamine. The genetic organization of the 89 bp pdxR-pdxST intergenic region was elucidated by mapping the 59 ends of the respective transcripts, followed by detection of typical promoter sequences. Bioinformatic pattern searches and comparative genomics revealed three DNA motifs with the consensus sequence AAAGTGGW("/T)CTA, overlapping the deduced promoter sequences and serving as candidate DNA-binding sites for PdxR. DNA band shift assays with the purified PdxR protein demonstrated the specific binding of the transcription regulator to double-stranded 40-mer sequences containing the detected motifs, thereby confirming the direct regulatory role of PdxR in activating the expression of the pdxST genes.

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“…GlxR, a cAMP-responsive regulator, and RamA, a LuxR-type regulator, were first identified as the transcriptional repressor and activator, respectively, of the aceB gene, encoding malate synthase of the glyoxylate cycle (14,38). Both regulators not only activate gapA expression (15,31) but are also involved in expression of a number of genes for various physiological functions, including carbon and nitrogen metabolism, respiration, SOS and stress responses, and cell division (15,(39)(40)(41). However, in contrast to the mechanism by which SugR switches gene expression, how GlxR and RamA switch expression of genes involved in glucose and acetate metabolism in response to a carbon source provided is not fully understood.…”

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confidence: 99%

Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

et al. 2013

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The central carbon metabolism genes in Corynebacterium glutamicum are under the control of a transcriptional regulatory network composed of several global regulators. It is known that the promoter region of ramA, encoding one of these regulators, interacts with its gene product, RamA, as well as with the two other regulators, GlxR and SugR, in vitro and/or in vivo. Although RamA has been confirmed to repress its own expression, the roles of GlxR and SugR in ramA expression have remained unclear. In this study, we examined the effects of GlxR binding site inactivation on expression of the ramA promoter-lacZ fusion in the genetic background of single and double deletion mutants of sugR and ramA. In the wild-type background, the ramA promoter activity was reduced to undetectable levels by the introduction of mutations into the GlxR binding site but increased by sugR deletion, indicating that GlxR and SugR function as the transcriptional activator and repressor, respectively. The marked repression of ramA promoter activity by the GlxR binding site mutations was largely compensated for by deletions of sugR and/or ramA. Furthermore, ramA promoter activity in the ramA-sugR double mutant was comparable to that in the ramA mutant but was significantly higher than that in the sugR mutant. Taken together, it is likely that the level of ramA expression is dynamically balanced by GlxR-dependent activation and repression by RamA along with SugR in response to perturbation of extracellular and/or intracellular conditions. These findings add multiple regulatory loops to the transcriptional regulatory network model in C. glutamicum.

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The GlxR regulon of the amino acid producer Corynebacterium glutamicum: Detection of the corynebacterial core regulon and integration into the transcriptional regulatory network model

Cited by 64 publications

References 47 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

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

Positive transcriptional control of the pyridoxal phosphate biosynthesis genes pdxST by the MocR-type regulator PdxR of Corynebacterium glutamicum ATCC 13032

Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

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