COLL 4 |
| Teruhisa Hirai, Jürgen A.W. Heymann, Dan Shi, and Sriram Subramaniam. NCI, National Cancer Institute, NIH, Bethesda, MD 20892-8008 |
| Membrane proteins that belong to the Major Facilitator Superfamily (MFS) are found in organisms across the evolutionary spectrum and mediate the transport of a variety of substrates ranging from small metabolites to neurotransmitters. Using electron crystallography, we have determined the three-dimensional structure of a representative member of this superfamily, the oxalate transporter OxlT at 6.5 Å resolution. The helix arrangement that we deduced for OxlT is identical to that of two other proteins (GlpT and LacY) in the same family whose structures have been determined recently by X-ray crystallography. From a detailed comparison of these structures, we show that while the reported structures of LacY and GlpT reflect "cytoplasmically-open" states of MFS proteins, the substrate-bound state of OxlT reflects a more "symmetric" state. By combining structural information from these two states, we have arrived at a general molecular mechanism for the protein conformational changes that are likely to be at the heart of substrate transport in all MFS proteins. |
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Bio-Colloids
8:30 AM-11:30 AM, Sunday, March 28, 2004 Marriott -- Grand Ballroom J, Oral
Division of Colloid and Surface Chemistry |