title: Dynamic PIN-FORMED auxin efflux carrier phosphorylation at the plasma membrane controls auxin efflux-dependent growth.
abstract: The directional distribution of the phytohormone auxin is essential for plant development. Directional auxin transport is mediated by the polarly distributed PIN-FORMED (PIN) auxin efflux carriers. We have previously shown that efficient PIN1-mediated auxin efflux requires activation through phosphorylation at the four serines S1-S4 in Arabidopsis thaliana The Brefeldin A (BFA)-sensitive D6 PROTEIN KINASE (D6PK) and the BFA-insensitive PINOID (PID) phosphorylate and activate PIN1 through phosphorylation at all four phosphosites. PID, but not D6PK, can also induce PIN1 polarity shifts, seemingly through phosphorylation at S1-S3. The differential effects of D6PK and PID on PIN1 polarity had so far been attributed to their differential phosphosite preference for the four PIN1 phosphosites. We have mapped PIN1 phosphorylation at S1-S4 in situ using phosphosite-specific antibodies. We detected phosphorylation at PIN1 phosphosites at the basal (rootward) as well as the apical (shootward) plasma membrane in different root cell types, in embryos, and shoot apical meristems. Thereby, PIN1 phosphorylation at all phosphosites generally followed the predominant PIN1 distribution but was not restricted to specific polar sides of the cells. PIN1 phosphorylation at the basal and apical plasma membrane was differentially sensitive to BFA treatments, suggesting the involvement of different protein kinases or trafficking mechanisms in PIN1 phosphorylation control. We conclude that phosphosite preferences are not sufficient to explain the differential effects of D6PK and PID on PIN1 polarity, and suggest that a more complex model is needed to explain the effects of PID.
authors.affiliation: Plant Systems Biology, Technical University of Munich, 85354 Freising, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Weller
authors.affiliation: Plant Systems Biology, Technical University of Munich, 85354 Freising, Germany.
authors.forename: Melina
authors.initials: M
authors.lastname: Zourelidou
authors.affiliation: Plant Systems Biology, Technical University of Munich, 85354 Freising, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Frank
authors.affiliation: Plant Systems Biology, Technical University of Munich, 85354 Freising, Germany.
authors.forename: Inês C R
authors.initials: IC
authors.lastname: Barbosa
authors.affiliation: Department of Cell Biology and Biochemistry, Regensburg University, 93053 Regensburg, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Fastner
authors.affiliation: Developmental Genetics, Center for Plant Molecular Biology, 72076 Tübingen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Richter
authors.affiliation: Developmental Genetics, Center for Plant Molecular Biology, 72076 Tübingen, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Jürgens
authors.affiliation: Department of Cell Biology and Biochemistry, Regensburg University, 93053 Regensburg, Germany.
authors.forename: Ulrich Z
authors.initials: UZ
authors.lastname: Hammes
authors.affiliation: Plant Systems Biology, Technical University of Munich, 85354 Freising, Germany; claus.schwechheimer@wzw.tum.de.
authors.forename: Claus
authors.initials: C
authors.lastname: Schwechheimer
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001692:Biological Transport; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D018519:Meristem / Q000378:metabolism; D009928:Organ Specificity; D010766:Phosphorylation / Q000187:drug effects; D018514:Plant Structures / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021381:Protein Transport; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D020126:Brefeldin A; C585918:D6PK protein, Arabidopsis; D011494:Protein Kinases; C405165:PINOID protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases
keywords: Arabidopsis; PIN1; auxin transport; polarity; protein kinase