The INA complex facilitates assembly of the peripheral stalk of the mitochondrial F1Fo-ATP synthase
18.06.2014
Lytovchenko O, Naumenko N, Oeljeklaus S, Schmidt B, von der Malsburg K, Deckers M, Warscheid B, van der Laan M, Rehling
EMBO J. 2014;33(15):1624-38
Eukaryotic cells synthesize the vast majority of ATP through a process termed oxidative phosphorylation, which takes place in the cristae domains of the inner mitochondrial membrane. The proton gradient across the inner mitochondrial membrane generated through the activity of the respiratory chain drives ATP production by the F1Fo-ATP synthase complex. Thus, efficient biogenesis of this key molecular machine is of central importance for cellular energy metabolism. Whereas a number of assembly factors have been described that assist the biogenesis of the membrane-embedded Fo-domain and the catalytic F1-domain of ATP synthase, it remained unclear how the proper assembly of the outer stalk domain that links the F1 and Fo portions of the complex is ensured. We now report on the identification and characterization of the inner membrane assembly complex (INAC) that transiently associates with an ATP synthase assembly intermediate containing the outer stalk domain, but not with mature ATP synthase complexes. The mitochondrial inner membrane proteins Ina17 and Ina22 are constituents of INAC. Deletion of the corresponding genes in baker's yeast (Saccharomyces cerevisiae) inhibits the assembly of outer stalk subunits with ATP synthase complexes leading to an impaired coupling of the F1 and Fo domains and poor growth of yeast cells under respiratory conditions.
