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

Julia Frunzke,Sonja Hasenbein,Michael Bott,Cornelia Gätgens,Verena Engels

doi:10.1111/j.1365-2958.2007.06020.x

Julia Frunzke, Sonja Hasenbein + Show 3 more

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https://doi.org/10.1111/j.1365-2958.2007.06020.x

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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 EIIGlc permease of the glucose phosphotransferase system (PTS) is activated by GntR1 and GntR2. Gluconate and glucono-δ-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.

Highlights

Corynebacterium glutamicum is a predominantly aerobic, biotin-auxotrophic Gram-positive soil bacterium that was isolated in Japan owing to its ability to excrete L-glutamate under biotin-limiting growth conditions (Kinoshita et al, 1957)
Corynebacterium glutamicum is a Gram-positive soil bacterium that prefers the simultaneous catabolism of different carbon sources rather than their sequential utilization
GntR1 and GntR2 strongly repress the genes encoding gluconate permease, gluconate kinase, and 6phosphogluconate dehydrogenase and weakly the pentose phosphate pathway genes organized in the tkt-tal-zwf-opcA-devB cluster

Summary

Introduction

Corynebacterium glutamicum is a predominantly aerobic, biotin-auxotrophic Gram-positive soil bacterium that was isolated in Japan owing to its ability to excrete L-glutamate under biotin-limiting growth conditions (Kinoshita et al, 1957). It is used today for the industrial production of more than two million tons of amino acids per year, mainly L-glutamate and L-lysine. This species has become a model organism of the Corynebacterineae, a suborder of the Actinomycetales which comprises the genus Mycobacterium. In recent studies several transcriptional regulators involved in the regulation of central metabolic pathways in C. glutamicum were identified and characterized, knowledge about transcriptional regulation of genes involved in gluconate metabolism and pentose phosphate pathway is scarce (Gerstmeir et al, 2004; Kim et al, 2004; Krug et al, 2005; Cramer et al, 2006; Engels and Wendisch, 2007; Wennerhold et al, 2005; Bott, 2007)

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