OdhI dephosphorylation kinetics during different glutamate production processes involving Corynebacterium glutamicum

Abstract

In Corynebacterium glutamicum, the activity of the 2-oxoglutarate dehydrogenase complex was shown to be controlled by the phosphorylation of a 15-kDa protein OdhI by different serine/threonine protein kinases. In this paper, the phosphorylation status and kinetics of OdhI dephosphorylation were assessed during glutamate producing processes triggered by either a biotin limitation or a temperature upshock from 33 degrees C to 39 degrees C. A dephosphorylation of OdhI in C. glutamicum 2262 was observed during the biotin-limited as well as the temperature-induced glutamate-producing process. Deletion of pknG in C. glutamicum 2262 did not affect the phosphorylation status of OdhI during growth and glutamate production phases triggered by a temperature upshock, though a 40% increase in the specific glutamate production rate was measured. These results suggest that, under the conditions analyzed, PknG is not the kinase responsible for the phosphorylation of OdhI in C. glutamicum 2262. The phosphorylation status of OdhI alone is, as expected, not the only parameter that determines the performance of a specific strain, as no clear relation between the specific glutamate production rate and OdhI phosphorylation level was demonstrated.