Glutamate production by Corynebacterium glutamicum: dependence on the oxoglutarate dehydrogenase inhibitor protein OdhI and protein kinase PknG.
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.
Schultz
Christian
C
Institut für Biotechnologie 1, Forschungszentrum Jülich, 52425, Jülich, Germany.
Niebisch
Axel
A
Gebel
Lena
L
Bott
Michael
M
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001709:Biotechnology; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004791:Enzyme Inhibitors / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial; D018698:Glutamic Acid / Q000096:biosynthesis*; D007655:Ketoglutarate Dehydrogenase Complex / Q000037:antagonists & inhibitors*; D007700:Kinetics; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004791:Enzyme Inhibitors; D018698:Glutamic Acid; D007655:Ketoglutarate Dehydrogenase Complex; D011494:Protein Kinases