Glutamate production by Corynebacterium glutamicum: dependence on the oxoglutarate dehydrogenase inhibitor protein OdhI and protein kinase PknG

Appl Microbiol Biotechnol. 2007 Sep;76(3):691-700. doi: 10.1007/s00253-007-0933-9. Epub 2007 Apr 17.

Abstract

We recently showed that the activity of the 2-oxoglutarate dehydrogenase complex (ODHC) in Corynebacterium glutamicum is controlled by a novel regulatory mechanism that involves a 15-kDa protein called OdhI and serine/threonine protein kinase G (PknG). In its unphosphorylated state, OdhI binds to the E1 subunit (OdhA) of ODHC and, thereby, inhibits its activity. Inhibition is relieved by phosphorylation of OdhI at threonine-14 by PknG under conditions requiring high ODHC activity. In this work, evidence is provided that the dephosphorylation of phosphorylated OdhI is catalyzed by a phospho-Ser/Thr protein phosphatase encoded by the gene cg0062, designated ppp. As a decreased ODHC activity is important for glutamate synthesis, we investigated the role of OdhI and PknG for glutamate production under biotin limitation and after addition of Tween-40, penicillin, or ethambutol. A DeltaodhI mutant formed only 1-13% of the glutamate synthesized by the wild type. Thus, OdhI is essential for efficient glutamate production. The effect of a pknG deletion on glutamate synthesis was dependent on the induction conditions. Under strong biotin limitation and in the presence of ethambutol, the DeltapknG mutant showed significantly increased glutamate production, offering a new way to improve production strains.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Biotechnology
  • Corynebacterium glutamicum / genetics
  • Corynebacterium glutamicum / growth & development
  • Corynebacterium glutamicum / metabolism*
  • DNA, Bacterial / genetics
  • Enzyme Inhibitors / metabolism
  • Gene Deletion
  • Genes, Bacterial
  • Glutamic Acid / biosynthesis*
  • Ketoglutarate Dehydrogenase Complex / antagonists & inhibitors*
  • Kinetics
  • Phosphorylation
  • Plasmids / genetics
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • Enzyme Inhibitors
  • Glutamic Acid
  • Ketoglutarate Dehydrogenase Complex
  • Protein Kinases