The novel component Kgd4 recruits the E3 subunit to the mitochondrial ?-ketoglutarate dehydrogenase
27.08.2014
Heublein M, Burguillos MA, Vögtle FN, Teixeira PF, Imhof A, Meisinger C, Ott M.
Mol Biol Cell. 2014;25(21):3342-9
The mitochondrial citric acid cycle is a central hub of cellular metabolism, providing intermediates for biosynthetic pathways as well as channeling electrons to the respiratory chain complexes. Here, we elucidated the composition and organization of the multienzyme complex ?-ketoglutarate dehydrogenase. In addition to the three classical E1-E3 subunits, we identified a novel component, Kgd4 (Ymr31/MRPS36), which was previously assigned to be a subunit of the mitochondrial ribosome. Biochemical analyses demonstrate that this protein plays an evolutionary conserved role in the organization of mitochondrial ?-ketoglutarate dehydrogenase complexes of fungi and animals. By binding to both the E1-E2 core and the E3 subunits, Kgd4 proteins act as molecular adaptors that are necessary to form a stable ?-ketoglutarate dehydrogenase enzyme complex. Our work thus reveals a novel subunit of a key citric acid cycle enzyme and shows how this large complex is organized.
