The FHA domain of OdhI interacts with the carboxyterminal 2-oxoglutarate dehydrogenase domain of OdhA in Corynebacterium glutamicum.

In Corynebacterium glutamicum, the unphosphorylated 15-kDa OdhI protein inhibits the activity of the 2-oxoglutarate dehydrogenase complex (ODHc) by binding to OdhA, which in corynebacteria and mycobacteria is a large fusion protein with two major domains exhibiting structural features of E1o and E2 proteins. Using copurification and surface plasmon resonance experiments with different OdhI and OdhA length variants it was shown that the entire forkhead-associated (FHA) domain of OdhI and the C-terminal dehydrogenase domain of OdhA are required for interaction. The FHA domain was also sufficient for inhibition of ODHc activity. Phosphorylated OdhI was binding-incompetent and did not inhibit ODHc activity.