| The Arabidopsis concentration-dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis. | |
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MedLine Citation:
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PMID: 21992190 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Arabidopsis ATP-binding cassette B4 (ABCB4) is a root-localised auxin efflux transporter with reported auxin uptake activity in low auxin concentrations. Results reported here demonstrate that ABCB4 is a substrate-activated regulator of cellular auxin levels. The contribution of ABCB4 to shootward auxin movement at the root apex increases with auxin concentration, but, in root hair elongation assays, ABCB4-mediated uptake is evident at low concentrations as well. Uptake kinetics of ABCB4 heterologously expressed in S. pombe differed from the saturation kinetics of AUX1 as uptake converted to efflux at threshold IAA concentrations. The concentration dependence of ABCB4 appears to be a direct effect on transporter activity, as ABCB4 expression and ABCB4 plasma membrane (PM) localisation at the root apex are relatively insensitive to changes in auxin concentration. However, PM localization of ABCB4 decreases with 1-naphthylphthalamic acid (NPA) treatment. Unlike other plant ABCBs studied to date and consistent with decreased detergent solubility, ABCB4(pro) :ABCB4-GFP is partially internalised in all cell types by 0.05% DMSO, but not 0.1% ethanol. In trichoblasts, ABCB4(pro) :ABCB4-GFP PM signals are reduced by >200 nM indole-3-acetic-acid (IAA) and 2,4-dichlorophenoxyacetic acid (2,4-D). In heterologous systems and in planta, ABCB4 transports benzoic acid with weak affinity, but not the oxidative catabolism products oxindole-3-acetic-acid and 2-oxindole-3-acetyl-β-D-glucose. ABCB4 mediates uptake, but not efflux, of the synthetic auxin 2,4-D in cells lacking AUX1 activity. Results presented here suggest that 2,4-D is a non-competitive inhibitor of IAA transport by ABCB4 and indicate that ABCB4 is a target of 2,4-D herbicidal activity. © 2011 The Authors. The Plant Journal© 2011 Blackwell Publishing Ltd. |
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Authors:
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Martin Kubeš; Haibing Yang; Gregory L Richter; Yan Cheng; Ewa Młodzińska; Xia Wang; Joshua J Blakeslee; Nicola Carraro; Jan Petrášek; Eva Zažímalová; Klára Hoyerová; Wendy Ann Peer; Angus S Murphy |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-10-12 |
Journal Detail:
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Title: The Plant journal : for cell and molecular biology Volume: - ISSN: 1365-313X ISO Abbreviation: - Publication Date: 2011 Oct |
Date Detail:
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Created Date: 2011-10-13 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9207397 Medline TA: Plant J Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2011 Blackwell Publishing Ltd and the Society for Experimental Biology. |
Affiliation:
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Institute of Experimental Botany, the Academy of Sciences of the Czech Republic, Rozvojová 263, CZ-165 02 Prague 6, Czech Republic Department of Horticulture, Purdue University, West Lafayette, IN 47907-2010, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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