Glutamate production by <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis>: dependence on the oxoglutarate dehydrogenase inhibitor protein OdhI and protein kinase PknG |
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Authors: | Christian Schultz Axel Niebisch Lena Gebel Michael Bott |
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Institution: | (1) Institut für Biotechnologie 1, Forschungszentrum Jülich, 52425 Jülich, Germany |
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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 ΔodhI 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 ΔpknG mutant showed significantly increased glutamate production, offering a new way to improve production strains.
Dedicated to Prof. Dr. Hermann Sahm on the occasion of his 65th birthday |
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Keywords: | Corynebacterium glutamicum Glutamate OdhI 2-Oxoglutarate dehydrogenase Oxoglutarate dehydrogenase inhibitor PknG Serine/threonine protein kinase |
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