Limits...
Co-ordinated regulation of gluconate catabolism and glucose uptake in Corynebacterium glutamicum by two functionally equivalent transcriptional regulators, GntR1 and GntR2.

Frunzke J, Engels V, Hasenbein S, Gätgens C, Bott M - Mol. Microbiol. (2007)

Bottom Line: Gluconate and glucono-delta-lactone interfere with binding of GntR1 and GntR2 to their target promoters, leading to a derepression of the genes involved in gluconate catabolism and reduced ptsG expression.A mutant lacking both gntR1 and gntR2 shows a 60% lower glucose uptake rate and growth rate than the wild type when cultivated on glucose as sole carbon source.This growth defect can be complemented by plasmid-encoded GntR1 or GntR2.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany.

ABSTRACT
Corynebacterium glutamicum is a Gram-positive soil bacterium that prefers the simultaneous catabolism of different carbon sources rather than their sequential utilization. This type of metabolism requires an adaptation of the utilization rates to the overall metabolic capacity. Here we show how two functionally redundant GntR-type transcriptional regulators, designated GntR1 and GntR2, co-ordinately regulate gluconate catabolism and glucose uptake. GntR1 and GntR2 strongly repress the genes encoding gluconate permease (gntP), gluconate kinase (gntK), and 6-phosphogluconate dehydrogenase (gnd) and weakly the pentose phosphate pathway genes organized in the tkt-tal-zwf-opcA-devB cluster. In contrast, ptsG encoding the EII(Glc) permease of the glucose phosphotransferase system (PTS) is activated by GntR1 and GntR2. Gluconate and glucono-delta-lactone interfere with binding of GntR1 and GntR2 to their target promoters, leading to a derepression of the genes involved in gluconate catabolism and reduced ptsG expression. To our knowledge, this is the first example for gluconate-dependent transcriptional control of PTS genes. A mutant lacking both gntR1 and gntR2 shows a 60% lower glucose uptake rate and growth rate than the wild type when cultivated on glucose as sole carbon source. This growth defect can be complemented by plasmid-encoded GntR1 or GntR2.

Show MeSH
Experimentally identified GntR1/2 binding sites in the promoter regions of gntK, gntP, gnd and ptsG. The location of the central nucleotide of the 15 bp binding sites is indicated with respect to the transcriptional start site for gntK, gntP and ptsG, but with respect to the start codon for gnd. The orientation of the binding sites is indicated by plus and minus signs. The relevance of each binding site was confirmed by mutational analysis using gel shift assays with purified GntR1 and GntR2. Nucleotides shaded in black are conserved in all binding sites, those shaded in grey are identical in three of four binding sites.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2230225&req=5

fig07: Experimentally identified GntR1/2 binding sites in the promoter regions of gntK, gntP, gnd and ptsG. The location of the central nucleotide of the 15 bp binding sites is indicated with respect to the transcriptional start site for gntK, gntP and ptsG, but with respect to the start codon for gnd. The orientation of the binding sites is indicated by plus and minus signs. The relevance of each binding site was confirmed by mutational analysis using gel shift assays with purified GntR1 and GntR2. Nucleotides shaded in black are conserved in all binding sites, those shaded in grey are identical in three of four binding sites.

Mentions: Analysis of the promoter regions of gntP, gnd and ptsG by gel shift analyses with subfragments of the promoter regions also led to the identification of distinct sites involved in GntR1/2 binding (Fig. 7). The relevance of these sites was again confirmed by mutation studies which showed that an exchange of 3 bp within these sites prevented binding (data not shown). The binding sites were centred at position +2 with respect to the recently reported transcriptional start site of gntP (Letek et al., 2006) and at position −11 with respect to the start codon of gnd. In the case of ptsG, the binding site was centred at position −60 with respect to the transcriptional start site determined previously by primer extension experiments (Engels and Wendisch, 2007). These positions fit with a repressor function for gntP and gnd and an activator function for ptsG of GntR1/2. All GntR1/2 binding sites identified in this work are in reasonable agreement (1–2 mismatches) with a consensus operator site deduced for GntR-type regulators of the FadR subfamily (TNGTNNNACNA) (Rigali et al., 2002).


Co-ordinated regulation of gluconate catabolism and glucose uptake in Corynebacterium glutamicum by two functionally equivalent transcriptional regulators, GntR1 and GntR2.

Frunzke J, Engels V, Hasenbein S, Gätgens C, Bott M - Mol. Microbiol. (2007)

Experimentally identified GntR1/2 binding sites in the promoter regions of gntK, gntP, gnd and ptsG. The location of the central nucleotide of the 15 bp binding sites is indicated with respect to the transcriptional start site for gntK, gntP and ptsG, but with respect to the start codon for gnd. The orientation of the binding sites is indicated by plus and minus signs. The relevance of each binding site was confirmed by mutational analysis using gel shift assays with purified GntR1 and GntR2. Nucleotides shaded in black are conserved in all binding sites, those shaded in grey are identical in three of four binding sites.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2230225&req=5

fig07: Experimentally identified GntR1/2 binding sites in the promoter regions of gntK, gntP, gnd and ptsG. The location of the central nucleotide of the 15 bp binding sites is indicated with respect to the transcriptional start site for gntK, gntP and ptsG, but with respect to the start codon for gnd. The orientation of the binding sites is indicated by plus and minus signs. The relevance of each binding site was confirmed by mutational analysis using gel shift assays with purified GntR1 and GntR2. Nucleotides shaded in black are conserved in all binding sites, those shaded in grey are identical in three of four binding sites.
Mentions: Analysis of the promoter regions of gntP, gnd and ptsG by gel shift analyses with subfragments of the promoter regions also led to the identification of distinct sites involved in GntR1/2 binding (Fig. 7). The relevance of these sites was again confirmed by mutation studies which showed that an exchange of 3 bp within these sites prevented binding (data not shown). The binding sites were centred at position +2 with respect to the recently reported transcriptional start site of gntP (Letek et al., 2006) and at position −11 with respect to the start codon of gnd. In the case of ptsG, the binding site was centred at position −60 with respect to the transcriptional start site determined previously by primer extension experiments (Engels and Wendisch, 2007). These positions fit with a repressor function for gntP and gnd and an activator function for ptsG of GntR1/2. All GntR1/2 binding sites identified in this work are in reasonable agreement (1–2 mismatches) with a consensus operator site deduced for GntR-type regulators of the FadR subfamily (TNGTNNNACNA) (Rigali et al., 2002).

Bottom Line: Gluconate and glucono-delta-lactone interfere with binding of GntR1 and GntR2 to their target promoters, leading to a derepression of the genes involved in gluconate catabolism and reduced ptsG expression.A mutant lacking both gntR1 and gntR2 shows a 60% lower glucose uptake rate and growth rate than the wild type when cultivated on glucose as sole carbon source.This growth defect can be complemented by plasmid-encoded GntR1 or GntR2.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biotechnologie 1, Forschungszentrum Jülich, D-52425 Jülich, Germany.

ABSTRACT
Corynebacterium glutamicum is a Gram-positive soil bacterium that prefers the simultaneous catabolism of different carbon sources rather than their sequential utilization. This type of metabolism requires an adaptation of the utilization rates to the overall metabolic capacity. Here we show how two functionally redundant GntR-type transcriptional regulators, designated GntR1 and GntR2, co-ordinately regulate gluconate catabolism and glucose uptake. GntR1 and GntR2 strongly repress the genes encoding gluconate permease (gntP), gluconate kinase (gntK), and 6-phosphogluconate dehydrogenase (gnd) and weakly the pentose phosphate pathway genes organized in the tkt-tal-zwf-opcA-devB cluster. In contrast, ptsG encoding the EII(Glc) permease of the glucose phosphotransferase system (PTS) is activated by GntR1 and GntR2. Gluconate and glucono-delta-lactone interfere with binding of GntR1 and GntR2 to their target promoters, leading to a derepression of the genes involved in gluconate catabolism and reduced ptsG expression. To our knowledge, this is the first example for gluconate-dependent transcriptional control of PTS genes. A mutant lacking both gntR1 and gntR2 shows a 60% lower glucose uptake rate and growth rate than the wild type when cultivated on glucose as sole carbon source. This growth defect can be complemented by plasmid-encoded GntR1 or GntR2.

Show MeSH