Simulation of the Coupling between Nucleotide Binding and Transmembrane Domains in the ATP Binding Cassette Transporter BtuCD

Jacon Sonne, Chriatian Kandt, Günther H. Peters, Flemming Y. Hansen, Morten Østergaard Jensen, D. Peter Tieleman

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    Abstract

    The nucleotide-induced structural rearrangements in ATP binding cassette (ABC) transporters, leading to substrate translocation, are largely unknown. We have modeled nucleotide binding and release in the vitamin B12 importer BtuCD using perturbed elastic network calculations and biased molecular dynamics simulations. Both models predict that nucleotide release decreases the tilt between the two transmembrane domains and opens the cytoplasmic gate. Nucleotide binding has the opposite effect. The observed coupling may be relevant for all ABC transporters because of the conservation of nucleotide binding domains and the shared role of ATP in ABC transporters. The rearrangements in the cytoplasmic gate region do not provide enough space for B12 to diffuse from the transporter pore into the cytoplasm, which could suggest that peristaltic forces are needed to exclude B12 from the transporter pore. Copyright © 2007 by the Biophysical Society.
    Original languageEnglish
    JournalBiophysical Journal
    Volume92
    Issue number8
    Pages (from-to)2727-2734
    Number of pages8
    ISSN0006-3495
    DOIs
    Publication statusPublished - 2007

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