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Regulation of ABCB1/PGP1-catalysed auxin transport by linker phosphorylation.

ABSTRACT: Polar transport of the plant hormone auxin is controlled by PIN- and ABCB/PGP-efflux catalysts. PIN polarity is regulated by the AGC protein kinase, PINOID (PID), while ABCB activity was shown to be dependent on interaction with the FKBP42, TWISTED DWARF1 (TWD1). Using co-immunoprecipitation (co-IP) and shotgun LC-MS/MS analysis, we identified PID as a valid partner in the interaction with TWD1. In-vitro and yeast expression analyses indicated that PID specifically modulates ABCB1-mediated auxin efflux in an action that is dependent on its kinase activity and that is reverted by quercetin binding and thus inhibition of PID autophosphorylation. Triple ABCB1/PID/TWD1 co-transfection in tobacco revealed that PID enhances ABCB1-mediated auxin efflux but blocks ABCB1 in the presence of TWD1. Phospho-proteomic analyses identified S634 as a key residue of the regulatory ABCB1 linker and a very likely target of PID phosphorylation that determines both transporter drug binding and activity. In summary, we provide evidence that PID phosphorylation has a dual, counter-active impact on ABCB1 activity that is coordinated by TWD1-PID interaction.

SUBMITTER: Henrichs S

PROVIDER: S-EPMC3395086 | biostudies-other | 2012 Jun

REPOSITORIES: biostudies-other

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Regulation of ABCB1/PGP1-catalysed auxin transport by linker phosphorylation.

Henrichs Sina S Wang Bangjun B Fukao Yoichiro Y Zhu Jinsheng J Charrier Laurence L Bailly Aurélien A Oehring Sophie C SC Linnert Miriam M Weiwad Matthias M Endler Anne A Nanni Paolo P Pollmann Stephan S Mancuso Stefano S Schulz Alexander A Geisler Markus M

The EMBO journal 20120501 13

Polar transport of the plant hormone auxin is controlled by PIN- and ABCB/PGP-efflux catalysts. PIN polarity is regulated by the AGC protein kinase, PINOID (PID), while ABCB activity was shown to be dependent on interaction with the FKBP42, TWISTED DWARF1 (TWD1). Using co-immunoprecipitation (co-IP) and shotgun LC-MS/MS analysis, we identified PID as a valid partner in the interaction with TWD1. In-vitro and yeast expression analyses indicated that PID specifically modulates ABCB1-mediated auxin ...[more]

PMID: 22549467

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Project description:BackgroundIndole-3-acetic acid (IAA), the most abundant auxin, is a growth promoter hormone involved in several developmental processes. Auxin homeostasis is very important to its function and this is achieved through the regulation of IAA biosynthesis, conjugation, degradation and transport. In grapevine, IAA plays an essential role during initial stages of berry development, since it delays fruitlet abscission by reducing the ethylene sensitivity in the abscission zone. For this reason, Continuous polar IAA transport to the pedicel is required. This kind of transport is controlled by IAA, which regulates its own movement by modifying the expression and localization of PIN-FORMED (PIN) auxin efflux facilitators that localize asymmetrically within the cell. On the other hand, the hormone gibberellin (GA) also activates the polar auxin transport by increasing PIN stability. In Vitis vinifera, fruitlet abscission occurs during the first two to three weeks after flowering. During this time, IAA and GA are present, however the role of these hormones in the control of polar auxin transport is unknown.ResultsIn this work, the use of radiolabeled IAA showed that auxin is basipetally transported during grapevine fruitlet abscission. This observation was further supported by immunolocalization of putative VvPIN proteins that display a basipetal distribution in pericarp cells. Polar auxin transport and transcripts of four putative VvPIN genes decreased in conjunction with increased abscission, and the inhibition of polar auxin transport resulted in fruit drop. GA3 and IAA treatments reduced polar auxin transport, but only GA3 treatment decreased VvPIN transcript abundance. When GA biosynthesis was blocked, IAA was capable to increase polar auxin transport, suggesting that its effect depends on GA content. Finally, we observed significant changes in the content of several IAA-related compounds during the abscission period.ConclusionsThese results provide evidence that auxin homeostasis plays a central role during grapevine initial fruit development and that GA and IAA controls auxin homeostasis by reducing polar auxin transport.

Dataset Information

Regulation of ABCB1/PGP1-catalysed auxin transport by linker phosphorylation.

Publications

Regulation of ABCB1/PGP1-catalysed auxin transport by linker phosphorylation.

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