Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 12 December 2008:
Vol. 322. no. 5908, pp. 1655 - 1661
DOI: 10.1126/science.1166777
Prev | Table of Contents | Next

Research Articles

A Competitive Inhibitor Traps LeuT in an Open-to-Out Conformation

Satinder K. Singh,1 Chayne L. Piscitelli,1,3 Atsuko Yamashita,4* Eric Gouaux1,2

Secondary transporters are workhorses of cellular membranes, catalyzing the movement of small molecules and ions across the bilayer and coupling substrate passage to ion gradients. However, the conformational changes that accompany substrate transport, the mechanism by which a substrate moves through the transporter, and principles of competitive inhibition remain unclear. We used crystallographic and functional studies on the leucine transporter (LeuT), a model for neurotransmitter sodium symporters, to show that various amino acid substrates induce the same occluded conformational state and that a competitive inhibitor, tryptophan (Trp), traps LeuT in an open-to-out conformation. In the Trp complex, the extracellular gate residues arginine 30 and aspartic acid 404 define a second weak binding site for substrates or inhibitors as they permeate from the extracellular solution to the primary substrate site, which demonstrates how residues that participate in gating also mediate permeation.

1 Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
2 Howard Hughes Medical Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
3 Department of Biochemistry and Molecular Biology, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
4 Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.

* Present address: RIKEN SPring-8 Center, 1-1-1, Kouto, Sayo, Hyogo 679-5148, Japan.

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Extracellular Loops 2 and 4 of GLYT2 Are Required for N-Arachidonylglycine Inhibition of Glycine Transport.
A. R. Edington, A. A. McKinzie, A. J. Reynolds, M. Kassiou, R. M. Ryan, and R. J. Vandenberg (2009)
J. Biol. Chem. 284, 36424-36430
   Abstract »    Full Text »    PDF »
Lipid bilayer regulation of membrane protein function: gramicidin channels as molecular force probes.
J. A. Lundbaek, S. A. Collingwood, H. I. Ingolfsson, R. Kapoor, and O. S. Andersen (2009)
J R Soc Interface
   Abstract »    Full Text »    PDF »
Ligand Effects on Cross-linking Support a Conformational Mechanism for Serotonin Transport.
Z. Tao, Y.-W. Zhang, A. Agyiri, and G. Rudnick (2009)
J. Biol. Chem. 284, 33807-33814
   Abstract »    Full Text »    PDF »
The Rocking Bundle: A Mechanism for Ion-Coupled Solute Flux by Symmetrical Transporters.
L. R. Forrest and G. Rudnick (2009)
Physiology 24, 377-386
   Abstract »    Full Text »    PDF »
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 »
Fluoxetine (Prozac) Binding to Serotonin Transporter Is Modulated by Chloride and Conformational Changes.
S. Tavoulari, L. R. Forrest, and G. Rudnick (2009)
J. Neurosci. 29, 9635-9643
   Abstract »    Full Text »    PDF »
Location of the Antidepressant Binding Site in the Serotonin Transporter: IMPORTANCE OF SER-438 IN RECOGNITION OF CITALOPRAM AND TRICYCLIC ANTIDEPRESSANTS.
J. Andersen, O. Taboureau, K. B. Hansen, L. Olsen, J. Egebjerg, K. Stromgaard, and A. S. Kristensen (2009)
J. Biol. Chem. 284, 10276-10284
   Abstract »    Full Text »    PDF »
Binding of an octylglucoside detergent molecule in the second substrate (S2) site of LeuT establishes an inhibitor-bound conformation.
M. Quick, A.-M. L. Winther, L. Shi, P. Nissen, H. Weinstein, and J. A. Javitch (2009)
PNAS 106, 5563-5568
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)