A hybrid TIM complex mediates protein import into hydrogenosomes of Trichomonas vaginalis

Hydrogenosomes are a specific type of mitochondria that have adapted for life under anaerobiosis. Limited availability of oxygen has resulted in the loss of the membrane- associated respiratory chain, and consequently in the generation of minimal inner membrane potential (), and inefficient ATP synthesis via substrate-level phosphorylation. The changes in energy metabolism are directly linked with the organelle biogenesis. In mitochondria, proteins are imported across the outer membrane via the Translocase of the Outer Membrane (TOM complex), while two Translocases of the Inner Membrane, TIM22, and TIM23, facilitate import to the inner membrane and matrix. TIM23-mediated steps are entirely dependent on and ATP hydrolysis, while TIM22 requires only . The character of the hydrogenosomal inner membrane translocase and the mechanism of translocation is currently unknown.