Structure of mitochondrial complex I

Mitochondrial complex I is the largest and most intricate enzyme of the respiratory chain. It comprises 14 central subunits that are conserved from bacteria to man and ~30 accessory subunits. The central subunits harbor the bioenergetic core functions and can be assigned to functional modules for NADH oxidation, ubiquinone reduction, and proton translocation. We have recently reported the X-ray structure of complex I from the aerobic yeast Yarrowia lipolytica at 3.6 to 3.9 Å resolution. The structure offers clues on the physiologically important active/deactive transition of complex I and on the catalytic cycle of redox-linked proton translocation.