A three-dimensional model for the substrate binding domain of the multidrug ATP binding cassette transporter LmrA
- Author(s)
- Gerhard Ecker, Karin Pleban, Stephan Kopp, Edina Csaszar, Gerrit J. Poelarends, Monique Putman, Dominik Kaiser, Wilhelmus N. Konings, Peter Chiba
- Abstract
Multidrug resistance presents a major obstacle to the treatment of infectious diseases and cancer. LmrA, a bacterial ATP-dependent multidrug transporter, mediates efflux of hydrophobic cationic substrates, including antibiotics. The substrate-binding domain of LmrA was identified by using photo-affinity ligands, proteolytic degradation of LmrA, and identification of ligand-modified peptide fragments with matrix-assisted laser desorption ionization/time of flight mass spectrometry. In the nonenergized state, labeling occurred in the a-helical transmembrane segments (TM) 3, 5 and 6 of the membrane-spanning domain. Upon nucleotide binding, the accessibility of TM5 for substrates increased, whereas that of TM6 decreased. Inverse changes were observed upon ATP-hydrolysis. An atomic-detail model of dimeric LmrA was generated based on the template structure of the homologous transporter MsbA from Vibrio cholerae, allowing a three-dimensional visualization of the substrate-binding domain. Labeling of TM3 of one monomer occurred in a predicted area of contact with TM5 or TM6 of the opposite monomer, indicating substrate-binding at the monomer/monomer interface. Inverse changes in the reactivity of TM segments 5 and 6 suggest that substrate binding and release involves a repositioning of these helices during the catalytic cycle.
- Organisation(s)
- Department of Biochemistry and Cell Biology
- External organisation(s)
- Medizinische Universität Wien, University of Groningen
- Journal
- Molecular Pharmacology
- Volume
- 66
- Pages
- 1169-1179
- No. of pages
- 11
- ISSN
- 0026-895X
- DOI
- https://doi.org/10.1124/mol.104.001420
- Publication date
- 2004
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 3012 Pharmacy, Pharmacology, Toxicology
- Sustainable Development Goals
- SDG 3 - Good Health and Well-being
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/74f0a508-08c4-4b6d-a534-dd9ea180d3bf