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  • Molecular dynamics and stru...
    Saura, Patricia; Kaila, Ville R.I.

    Biochimica et biophysica acta. Bioenergetics, 03/2019, Letnik: 1860, Številka: 3
    Journal Article

    NDH-1 is a gigantic redox-driven proton pump linked with respiration and cyclic electron flow in cyanobacterial cells. Based on experimentally resolved X-ray and cryo-EM structures of the respiratory complex I, we derive here molecular models of two isoforms of the cyanobacterial NDH-1 complex involved in redox-driven proton pumping (NDH-1L) and CO2-fixation (NDH-1MS). Our models show distinct structural and dynamic similarities to the core architecture of the bacterial and mammalian respiratory complex I. We identify putative plastoquinone-binding sites that are coupled by an electrostatic wire to the proton pumping elements in the membrane domain of the enzyme. Molecular simulations suggest that the NDH-1L isoform undergoes large-scale hydration changes that support proton-pumping within antiporter-like subunits, whereas the terminal subunit of the NDH-1MS isoform lacks such structural motifs. Our work provides a putative molecular blueprint for the complex I-analogue in the photosynthetic energy transduction machinery and demonstrates that general mechanistic features of the long-range proton-pumping machinery are evolutionary conserved in the complex I-superfamily. Display omitted •Molecular models of the cyanobacterial NDH-1 complex were computationally derived•NDH-1 shows distinct structural and dynamical similarities to respiratory complex I•Plastoquinone binding sites electrostatically interact with proton pumping elements•Plastoquinol dynamics couple with conformational changes in the membrane domain•Four proton channels were identified in the antiporter-like subunits in NDH-1L