title: The type B phosphatidylinositol-4-phosphate 5-kinase 3 is essential for root hair formation in Arabidopsis thaliana.
abstract: Root hairs are extensions of root epidermal cells and a model system for directional tip growth of plant cells. A previously uncharacterized Arabidopsis thaliana phosphatidylinositol-4-phosphate 5-kinase gene (PIP5K3) was identified and found to be expressed in the root cortex, epidermal cells, and root hairs. Recombinant PIP5K3 protein was catalytically active and converted phosphatidylinositol-4-phosphate to phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2]. Arabidopsis mutant plants homozygous for T-DNA-disrupted PIP5K3 alleles were compromised in root hair formation, a phenotype complemented by expression of wild-type PIP5K3 cDNA under the control of a 1500-bp PIP5K3 promoter fragment. Root hair-specific PIP5K3 overexpression resulted in root hair deformation and loss of cell polarity with increasing accumulation of PIP5K3 transcript. Using reestablishment of root hair formation in T-DNA mutants as a bioassay for physiological functionality of engineered PIP5K3 variants, catalytic activity was found to be essential for physiological function, indicating that PtdIns(4,5)P2 formation is required for root hair development. An N-terminal domain containing membrane occupation and recognition nexus repeats, which is not required for catalytic activity, was found to be essential for the establishment of root hair growth. Fluorescence-tagged PIP5K3 localized to the periphery of the apical region of root hair cells, possibly associating with the plasma membrane and/or exocytotic vesicles. Transient heterologous expression of full-length PIP5K3 in tobacco (Nicotiana tabacum) pollen tubes increased plasma membrane association of a PtdIns(4,5)P2-specific reporter in these tip-growing cells. The data demonstrate that root hair development requires PIP5K3-dependent PtdIns(4,5)P2 production in the apical region of root hair cells.
authors.affiliation: Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Stenzel
authors.forename: Till
authors.initials: T
authors.lastname: Ischebeck
authors.forename: Sabine
authors.initials: S
authors.lastname: König
authors.forename: Anna
authors.initials: A
authors.lastname: Hołubowska
authors.forename: Marta
authors.initials: M
authors.lastname: Sporysz
authors.forename: Bettina
authors.initials: B
authors.lastname: Hause
authors.forename: Ingo
authors.initials: I
authors.lastname: Heilmann
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D002384:Catalysis; D002462:Cell Membrane / Q000201:enzymology; D004269:DNA, Bacterial; D004789:Enzyme Activation; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D050505:Mutant Proteins / Q000378:metabolism; D010641:Phenotype; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology / Q000201:enzymology; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D053205:Pollen Tube / Q000201:enzymology; D021381:Protein Transport; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D004269:DNA, Bacterial; D007527:Isoenzymes; D050505:Mutant Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; C036483:T-DNA; C037178:phosphatidylinositol 4-phosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase