The global repressor SugR controls expression of genes of glycolysis and of the L-lactate dehydrogenase LdhA in Corynebacterium glutamicum

J Bacteriol. 2008 Dec;190(24):8033-44. doi: 10.1128/JB.00705-08. Epub 2008 Oct 10.

Abstract

The transcriptional regulator SugR from Corynebacterium glutamicum represses genes of the phosphoenolpyruvate-dependent phosphotransferase system (PTS). Growth experiments revealed that the overexpression of sugR not only perturbed the growth of C. glutamicum on the PTS sugars glucose, fructose, and sucrose but also led to a significant growth inhibition on ribose, which is not taken up via the PTS. Chromatin immunoprecipitation combined with DNA microarray analysis and gel retardation experiments were performed to identify further target genes of SugR. Gel retardation analysis confirmed that SugR bound to the promoter regions of genes of the glycolytic enzymes 6-phosphofructokinase (pfkA), fructose-1,6-bisphosphate aldolase (fba), enolase (eno), pyruvate kinase (pyk), and NAD-dependent L-lactate dehydrogenase (ldhA). The deletion of sugR resulted in increased mRNA levels of eno, pyk, and ldhA in acetate medium. Enzyme activity measurements revealed that SugR-mediated repression affects the activities of PfkA, Fba, and LdhA in vivo. As the deletion of sugR led to increased LdhA activity under aerobic and under oxygen deprivation conditions, L-lactate production by C. glutamicum was determined. The overexpression of sugR reduced L-lactate production by about 25%, and sugR deletion increased L-lactate formation under oxygen deprivation conditions by threefold. Thus, SugR functions as a global repressor of genes of the PTS, glycolysis, and fermentative L-lactate dehydrogenase in C. glutamicum.

MeSH terms

  • Anaerobiosis
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Chromatin Immunoprecipitation
  • Corynebacterium glutamicum / genetics*
  • Corynebacterium glutamicum / metabolism
  • DNA, Bacterial / genetics
  • Electrophoretic Mobility Shift Assay
  • Fermentation
  • Fructose / metabolism
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial
  • Glucose / metabolism
  • Glycolysis*
  • L-Lactate Dehydrogenase / genetics
  • L-Lactate Dehydrogenase / metabolism*
  • Lactic Acid / biosynthesis
  • Oligonucleotide Array Sequence Analysis
  • Phosphoenolpyruvate Sugar Phosphotransferase System / metabolism*
  • Plasmids
  • Promoter Regions, Genetic
  • Regulon
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Ribose / metabolism

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • Repressor Proteins
  • Fructose
  • Lactic Acid
  • Ribose
  • L-Lactate Dehydrogenase
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • Glucose