The central cavity of ABCB1 undergoes alternating access during ATP hydrolysis

van Wonderen, Jessica H., McMahon, Róisin M., O'Mara, Megan L., McDevitt, Christopher A., Thomson, Andrew J., Kerr, Ian D., MacMillan, Fraser and Callaghan, Richard (2014) The central cavity of ABCB1 undergoes alternating access during ATP hydrolysis. FEBS Journal, 281 9: 2190-2201. doi:10.1111/febs.12773

Author van Wonderen, Jessica H.
McMahon, Róisin M.
O'Mara, Megan L.
McDevitt, Christopher A.
Thomson, Andrew J.
Kerr, Ian D.
MacMillan, Fraser
Callaghan, Richard
Title The central cavity of ABCB1 undergoes alternating access during ATP hydrolysis
Journal name FEBS Journal   Check publisher's open access policy
ISSN 1742-464X
Publication date 2014-05
Year available 2014
Sub-type Article (original research)
DOI 10.1111/febs.12773
Open Access Status DOI
Volume 281
Issue 9
Start page 2190
End page 2201
Total pages 12
Place of publication Oxford, UK
Publisher Wiley-Blackwell Publishing
Collection year 2015
Language eng
Formatted abstract
Understanding the process that underlies multidrug recognition and efflux by P-glycoprotein (ABCB1) remains a key biological challenge. Structural data have recently become available for the murine and Caenorhabditis elegans homologues of ABCB1; however all structures were obtained in the absence of nucleotide. A feature of these structures was the presence of a central cavity that is inaccessible from the extracellular face of the protein. To determine the conformational dynamics of this region several residues in transmembrane helices TM6 (331, 343 and 354) and TM12 (980) were mutated to cysteine. Based upon structural predictions, these residues are proposed to line, or reside proximal to, the central cavity. The mutant isoforms were labelled with a paramagnetic probe enabling the application of EPR spectroscopic methods. Power saturation EPR spectra were recorded in the presence of hydrophobic (O2) or hydrophilic (NiEDDA) quenching agents to study the local environment of each residue. ABCB1 was trapped in both its nucleotide-bound and post-hydrolytic conformations and EPR spectra were again recorded in the presence and absence of quenching agents. The EPR line shapes provide information on the movements of these residues within TM6 and TM12 during ATP hydrolysis. Rationalization of the data with molecular dynamic simulations indicates that the cavity is converted to a configuration open to the aqueous phase following nucleotide binding, thereby suggesting alternating access to the cavity on opposite sides of the membrane during translocation.
Keyword ABC transporter
Cancer chemotherapy
Membrane transport
Multidrug resistance
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
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Citation counts: TR Web of Science Citation Count  Cited 12 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 09 Apr 2014, 11:31:14 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences