Antagonistic Regulation of PIN Phosphorylation by PP2A and PINOID Directs Auxin Flux

Cell. 2007 Sep 21;130(6):1044-56. doi: 10.1016/j.cell.2007.07.033.

Abstract

In plants, cell polarity and tissue patterning are connected by intercellular flow of the phytohormone auxin, whose directional signaling depends on polar subcellular localization of PIN auxin transport proteins. The mechanism of polar targeting of PINs or other cargos in plants is largely unidentified, with the PINOID kinase being the only known molecular component. Here, we identify PP2A phosphatase as an important regulator of PIN apical-basal targeting and auxin distribution. Genetic analysis, localization, and phosphorylation studies demonstrate that PP2A and PINOID both partially colocalize with PINs and act antagonistically on the phosphorylation state of their central hydrophilic loop, hence mediating PIN apical-basal polar targeting. Thus, in plants, polar sorting by the reversible phosphorylation of cargos allows for their conditional delivery to specific intracellular destinations. In the case of PIN proteins, this mechanism enables switches in the direction of intercellular auxin fluxes, which mediate differential growth, tissue patterning, and organogenesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / embryology
  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Polarity
  • Endosomes / metabolism
  • Genotype
  • Indoleacetic Acids / metabolism*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Meristem / enzymology
  • Meristem / metabolism
  • Mutation
  • Phenotype
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Plants, Genetically Modified / embryology
  • Plants, Genetically Modified / enzymology
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / metabolism*
  • Protein Subunits / metabolism
  • Protein Transport
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Seedlings / enzymology
  • Seedlings / metabolism
  • Signal Transduction

Substances

  • Arabidopsis Proteins
  • Indoleacetic Acids
  • Membrane Transport Proteins
  • PIN1 protein, Arabidopsis
  • PIN2 protein, Arabidopsis
  • PIN4 protein, Arabidopsis
  • Protein Subunits
  • Recombinant Fusion Proteins
  • PINOID protein, Arabidopsis
  • Protein-Serine-Threonine Kinases
  • Phosphoprotein Phosphatases