Article abstract
Nature Structural & Molecular Biology 15, 730 - 737 (2008)
Published online: 8 June 2008 | doi:10.1038/nsmb.1434
Molecular mechanism of energy conservation in polysulfide respiration
Mika Jormakka1,2,3, Ken Yokoyama4,5, Takahiro Yano5, Masatada Tamakoshi6, Satoru Akimoto5, Tatsuro Shimamura7,8, Paul Curmi1 & So Iwata8,9,10
Abstract
Bacterial polysulfide reductase (PsrABC) is an integral membrane protein complex responsible for quinone-coupled reduction of polysulfide, a process important in extreme environments such as deep-sea vents and hot springs. We determined the structure of polysulfide reductase from Thermus thermophilus at 2.4-Å resolution, revealing how the PsrA subunit recognizes and reduces its unique polyanionic substrate. The integral membrane subunit PsrC was characterized using the natural substrate menaquinone-7 and inhibitors, providing a comprehensive representation of a quinone binding site and revealing the presence of a water-filled cavity connecting the quinone binding site on the periplasmic side to the cytoplasm. These results suggest that polysulfide reductase could be a key energy-conserving enzyme of the T. thermophilus respiratory chain, using polysulfide as the terminal electron acceptor and pumping protons across the membrane via a previously unknown mechanism.
- Department of Biophysics, University of New South Wales, Barker Street, Sydney, New South Wales 2052, Australia.
- Structural Biology Program, Centenary Institute of Cancer Medicine and Cell Biology, Locked Bag 6, Sydney, New South Wales 2042, Australia.
- Faculty of Medicine, Central Clinical School, University of Sydney, Sydney, New South Wales 2006, Australia.
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
- ICORP ATP-Synthesis Regulation Project, Japan Science and Technology Agency, 2-41 Aomi, Koto-ku, Tokyo, 135-0064, Japan.
- Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
- Structural Biophysics Laboratory, RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
- Japan Science and Technology Agency, ERATO, Human Crystallography Project, Yoshida Konoe, Sakyo-ku, Kyoto 606-851, Japan.
- Division of Molecular Biosciences, Membrane Protein Crystallography Group, Imperial College, Exhibition Road, London SW7 2AZ, United Kingdom.
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
Correspondence to: Mika Jormakka1,2,3 e-mail: m.jormakka@centenary.org.au
Correspondence to: So Iwata8,9,10 e-mail: s.iwata@imperial.ac.uk
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