Crystal Structure of the Maltose Transporter in a Pretranslocation Intermediate State
- Purdue
Adenosine triphosphate (ATP)-binding cassette (ABC) transporters convert chemical energy from ATP hydrolysis to mechanical work for substrate translocation. They function by alternating between two states, exposing the substrate-binding site to either side of the membrane. A key question that remains to be addressed is how substrates initiate the transport cycle. Using x-ray crystallography, we have captured the maltose transporter in an intermediate step between the inward- and outward-facing states. We show that interactions with substrate-loaded maltose-binding protein in the periplasm induce a partial closure of the MalK dimer in the cytoplasm. ATP binding to this conformation then promotes progression to the outward-facing state. These results, interpreted in light of biochemical and functional studies, provide a structural basis to understand allosteric communication in ABC transporters.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- AHANIH
- OSTI ID:
- 1023648
- Journal Information:
- Science, Vol. 332, Issue 06, 2011; ISSN 0193-4511
- Country of Publication:
- United States
- Language:
- ENGLISH
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