3D Reconstruction of the NADH:Ubiqinone Oxidoreductase (Complex I) from Yarrowia lipolytica Lacking Subunit NUMM

Complex I is the first enzyme of the respiratory chain in both the bacterial and the mitochondrial inner membranes. The mitochondrial enzyme from the aerobic yeast Yarrowia lipolytica has a molecular weight close to 1 MDa and contains at least 42 subunits. Complex I in all species exhibits an L-shape with two arms of similar length, one embedded in the membrane (membrane arm) and the other reaching into the mitochondrial matrix or the bacterial cytoplasm (matrix arm). NADH binds to the outer protrusion of the matrix arm and is oxidized. Concomitantly electrons are transferred to ubiquinone and four protons are translocated across the membrane. The four protons contribute to the membrane potential that is used by the F-ATPase to produce ATP.