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Structure and Molecular Mechanism of a Nucleobase–Cation–Symport-1 Family Transporter
Simone Weyand,1,2,3*Tatsuro Shimamura,2,3,4*Shunsuke Yajima,2,3*Shun'ichi Suzuki,5*Osman Mirza,2*Kuakarun Krusong,2||Elisabeth P. Carpenter,1,2Nicholas G. Rutherford,5Jonathan M. Hadden,5John O'Reilly,5Pikyee Ma,5Massoud Saidijam,5,6Simon G. Patching,5Ryan J. Hope,5Halina T. Norbertczak,5Peter C. J. Roach,5So Iwata,1,2,3,4,7¶Peter J. F. Henderson,5¶Alexander D. Cameron1,2,3
The nucleobase–cation–symport-1 (NCS1) transportersare essential components of salvage pathways for nucleobasesand related metabolites. Here, we report the 2.85-angstrom resolutionstructure of the NCS1 benzyl-hydantoin transporter, Mhp1, fromMicrobacterium liquefaciens. Mhp1 contains 12 transmembranehelices, 10 of which are arranged in two inverted repeats offive helices. The structures of the outward-facing open andsubstrate-bound occluded conformations were solved, showinghow the outward-facing cavity closes upon binding of substrate.Comparisons with the leucine transporter LeuTAa and the galactosetransporter vSGLT reveal that the outward- and inward-facingcavities are symmetrically arranged on opposite sides of themembrane. The reciprocal opening and closing of these cavitiesis synchronized by the inverted repeat helices 3 and 8, providingthe structural basis of the alternating access model for membranetransport.
1 Membrane Protein Laboratory, Diamond Light Source Limited, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE, UK. 2 Division of Molecular Biosciences, Membrane Protein Crystallography Group, Imperial College, London SW7 2AZ, UK. 3 Human Receptor Crystallography Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. 4 Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-Ku, Kyoto 606-8501, Japan. 5 Astbury Centre for Structural Molecular Biology, Institute for Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK. 6 School of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran. 7 Systems and Structural Biology Center, RIKEN, 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama 230-0045 Japan.
* These authors contributed equally to this work
Present address: Department of Bioscience, Tokyo Universityof Agriculture, Sakuragaoka 1-1-1, Setagaya-ku, Tokyo 156-8502,Japan.
Present address: Department of Medicinal Chemistry, Facultyof Pharmaceutical Sciences, University of Copenhagen, Universitetsparken2, DK-2100, Denmark.
|| Present address: Department of Biochemistry, Faculty of Science,Chulalongkorn University, Phyathai Road, Patumwan, Bangkok 10330,Thailand.
¶ To whom correspondence should be addressed. E-mail: s.iwata{at}imperial.ac.uk (S.I.); p.j.f.henderson{at}leeds.ac.uk (P.J.F.H.)
Role of Intramembrane Polar Residues in the YgfO Xanthine Permease: HIS-31 AND ASN-93 ARE CRUCIAL FOR AFFINITY AND SPECIFICITY, AND ASP-304 AND GLU-272 ARE IRREPLACEABLE.
Structure and Mechanism of a Na+-Independent Amino Acid Transporter.
P. L. Shaffer, A. Goehring, A. Shankaranarayanan, and E. Gouaux (2009)
Science
325, 1010-1014
|Abstract »|Full Text »|PDF »
Substrate Binding Tunes Conformational Flexibility and Kinetic Stability of an Amino Acid Antiporter.
C. A. Bippes, A. Zeltina, F. Casagrande, M. Ratera, M. Palacin, D. J. Muller, and D. Fotiadis (2009)
J. Biol. Chem.
284, 18651-18663
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An ab Initio Structural Model of a Nucleoside Permease Predicts Functionally Important Residues.
R. Valdes, S. Arastu-Kapur, S. M. Landfear, and U. Shinde (2009)
J. Biol. Chem.
284, 19067-19076
|Abstract »|Full Text »|PDF »
Role of the glutamate 185 residue in proton translocation mediated by the proton-coupled folate transporter SLC46A1.
E. S. Unal, R. Zhao, and I. D. Goldman (2009)
Am J Physiol Cell Physiol
297, C66-C74
|Abstract »|Full Text »|PDF »
Conserved Glutamate Residues Glu-343 and Glu-519 Provide Mechanistic Insights into Cation/Nucleoside Cotransport by Human Concentrative Nucleoside Transporter hCNT3.
M. D. Slugoski, K. M. Smith, A. M. L. Ng, S. Y. M. Yao, E. Karpinski, C. E. Cass, S. A. Baldwin, and J. D. Young (2009)
J. Biol. Chem.
284, 17266-17280
|Abstract »|Full Text »|PDF »
Substituted Cysteine Accessibility Method Analysis of Human Concentrative Nucleoside Transporter hCNT3 Reveals a Novel Discontinuous Region of Functional Importance within the CNT Family Motif (G/A)XKX3NEFVA(Y/M/F).
M. D. Slugoski, A. M. L. Ng, S. Y. M. Yao, C. C. Lin, R. Mulinta, C. E. Cass, S. A. Baldwin, and J. D. Young (2009)
J. Biol. Chem.
284, 17281-17292
|Abstract »|Full Text »|PDF »
Structure and Mechanism of an Amino Acid Antiporter.
X. Gao, F. Lu, L. Zhou, S. Dang, L. Sun, X. Li, J. Wang, and Y. Shi (2009)
Science
324, 1565-1568
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Transmembrane Domain 8 of the {gamma}-Aminobutyric Acid Transporter GAT-1 Lines a Cytoplasmic Accessibility Pathway into Its Binding Pocket.
Present address: Department of Bioscience, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya-ku, Tokyo 156-8502, Japan. 
Present address: Aminosciences Laboratories, Ajinomoto Company Incorporated, 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-8681, Japan. 
Present address: Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100, Denmark. 
