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Mutations in the Arabidopsis Peroxisomal ABC Transporter COMATOSE Allow Differentiation between Multiple Functions In Planta: Insights from an Allelic Series

Dietrich, D., Schmuths, H., Lousa, C.D., Baldwin, J.M., Baldwin, S.A., Baker, A., Theodoulou, F.A. and Holdsworth, M.J. (2009) Mutations in the Arabidopsis Peroxisomal ABC Transporter COMATOSE Allow Differentiation between Multiple Functions In Planta: Insights from an Allelic Series. Molecular Biology of the Cell, 20 (1). pp. 530-543. ISSN 1939-4586

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Abstract

COMATOSE (CTS), the Arabidopsis homologue of human Adrenoleukodystrophy protein (ALDP), is required for import of substrates for peroxisomal β-oxidation. A new allelic series and a homology model based on the bacterial ABC transporter, Sav1866, provide novel insights into structure-function relations of ABC subfamily D proteins. In contrast to ALDP, where the majority of mutations result in protein absence from the peroxisomal membrane, all CTS mutants produced stable protein. Mutation of conserved residues in the Walker A and B motifs in CTS nucleotide-binding domain (NBD) 1 resulted in a null phenotype but had little effect in NBD2, indicating that the NBDs are functionally distinct in vivo. Two alleles containing mutations in NBD1 outside the Walker motifs (E617K and C631Y) exhibited resistance to auxin precursors 2,4-dichlorophenoxybutyric acid (2,4-DB) and indole butyric acid (IBA) but were wild type in all other tests. The homology model predicted that the transmission interfaces are domain-swapped in CTS, and the differential effects of mutations in the conserved "EAA motif" of coupling helix 2 supported this prediction, consistent with distinct roles for each NBD. Our findings demonstrate that CTS functions can be separated by mutagenesis and the structural model provides a framework for interpretation of phenotypic data.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright © 2009 by The American Society for Cell Biology. Reproduced in accordance with the publisher's policy.
Academic Units: The University of Leeds > Faculty of Biological Sciences (Leeds) > Institute of Integrative and Comparative Biology (Leeds) > Centre for Plant Sciences (Leeds)
The University of Leeds > Faculty of Biological Sciences (Leeds) > Institute of Membrane and Systems Biology (Leeds)
Depositing User: Sherpa Assistant
Date Deposited: 29 Jan 2009 10:39
Last Modified: 08 Feb 2013 17:05
Published Version: http://dx.doi.org/10.1091/mbc.E08-07-0745
Status: Published
Publisher: The American Society for Cell Biology
Refereed: Yes
Identification Number: 10.1091/mbc.E08-07-0745
URI: http://eprints.whiterose.ac.uk/id/eprint/5429

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