Biomaterial Database

High-resolution structure and dynamics of mitochondrial complex I-Insights into the proton pumping mechanism. 2021

Kristian Parey, and Jonathan Lasham, and Deryck J Mills, and Amina Djurabekova, and Outi Haapanen, and Etienne Galemou Yoga, and Hao Xie, and Werner Kühlbrandt, and Vivek Sharma, and Janet Vonck, and Volker Zickermann

Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany.

Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is a 1-MDa membrane protein complex with a central role in energy metabolism. Redox-driven proton translocation by complex I contributes substantially to the proton motive force that drives ATP synthase. Several structures of complex I from bacteria and mitochondria have been determined, but its catalytic mechanism has remained controversial. We here present the cryo-EM structure of complex I from Yarrowia lipolytica at 2.1-Å resolution, which reveals the positions of more than 1600 protein-bound water molecules, of which ~100 are located in putative proton translocation pathways. Another structure of the same complex under steady-state activity conditions at 3.4-Å resolution indicates conformational transitions that we associate with proton injection into the central hydrophilic axis. By combining high-resolution structural data with site-directed mutagenesis and large-scale molecular dynamic simulations, we define details of the proton translocation pathways and offer insights into the redox-coupled proton pumping mechanism of complex I.