title: A protein kinase target of a PDK1 signalling pathway is involved in root hair growth in Arabidopsis.
abstract: Here we report on a lipid-signalling pathway in plants that is downstream of phosphatidic acid and involves the Arabidopsis protein kinase, AGC2-1, regulated by the 3'-phosphoinositide-dependent kinase-1 (AtPDK1). AGC2-1 specifically interacts with AtPDK1 through a conserved C-terminal hydrophobic motif that leads to its phosphorylation and activation, whereas inhibition of AtPDK1 expression by RNA interference abolishes AGC2-1 activity. Phosphatidic acid specifically binds to AtPDK1 and stimulates AGC2-1 in an AtPDK1-dependent manner. AtPDK1 is ubiquitously expressed in all plant tissues, whereas expression of AGC2-1 is abundant in fast-growing organs and dividing cells, and activated during re-entry of cells into the cell cycle after sugar starvation-induced G1-phase arrest. Plant hormones, auxin and cytokinin, synergistically activate the AtPDK1-regulated AGC2-1 kinase, indicative of a role in growth and cell division. Cellular localisation of GFP-AGC2-1 fusion protein is highly dynamic in root hairs and at some stages confined to root hair tips and to nuclei. The agc2-1 knockout mutation results in a reduction of root hair length, suggesting a role for AGC2-1 in root hair growth and development.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, UK.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Anthony
authors.forename: Rossana
authors.initials: R
authors.lastname: Henriques
authors.forename: Anne
authors.initials: A
authors.lastname: Helfer
authors.forename: Tamás
authors.initials: T
authors.lastname: Mészáros
authors.forename: Gabino
authors.initials: G
authors.lastname: Rios
authors.forename: Christa
authors.initials: C
authors.lastname: Testerink
authors.forename: Teun
authors.initials: T
authors.lastname: Munnik
authors.forename: Maria
authors.initials: M
authors.lastname: Deák
authors.forename: Csaba
authors.initials: C
authors.lastname: Koncz
authors.forename: László
authors.initials: L
authors.lastname: Bögre
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics / Q000502:physiology; D016193:G1 Phase / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D010766:Phosphorylation; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D016207:Cytokines; D007210:Indoleacetic Acids; D011494:Protein Kinases; D064413:3-Phosphoinositide-Dependent Protein Kinases; C501468:AGC2-1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases