title: A novel phosphatidylcholine-hydrolyzing phospholipase C induced by phosphate starvation in Arabidopsis.
abstract: During phosphate starvation, it is known that phospholipids are degraded, and conversely, a nonphosphorus galactolipid digalactosyldiacylglycerol accumulates in the root plasma membrane of plants. We report a novel phospholipase C that hydrolyzes phosphatidylcholine and is greatly induced in response to phosphate deprivation in Arabidopsis. Since phosphatidylcholine-hydrolyzing activity by phospholipase C was highly up-regulated in phosphate-deprived plants, gene expression of some phospholipase C was expected to be induced during phosphate starvation. Based on amino acid sequence similarity to a bacterial phosphatidylcholine-hydrolyzing phospholipase C, six putative phospholipase Cs were identified in the Arabidopsis genome, one of which, NPC4, showed significant transcriptional activation upon phosphate limitation. Molecular cloning and functional expression of NPC4 confirmed that the NPC4 gene encoded a functional phosphatidylcholine-hydrolyzing phospholipase C that did not require Ca(2+) for its activity. Subcellular localization analysis showed that NPC4 protein was highly enriched in the plasma membrane. Analyses of transferred DNA-tagged npc4 mutants revealed that disruption of NPC4 severely reduces the phosphatidylcholine-hydrolyzing phospholipase C activity in response to phosphate starvation. These results suggest that NPC4 plays an important role in the supply of both inorganic phosphate and diacylglycerol from membrane-localized phospholipids that would be used for phosphate supplementation and the replacement of polar lipids in the root plasma membrane during phosphate deprivation.
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-14 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Koichiro
authors.initials: K
authors.lastname: Awai
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Masuda
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Takamiya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000502:physiology; D001426:Bacterial Proteins / Q000737:chemistry; D015152:Blotting, Northern; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D017343:Genes, Plant; D018745:Genome, Plant; D006868:Hydrolysis; D050356:Lipid Metabolism; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000378:metabolism; D010940:Plant Proteins / Q000096:biosynthesis; D018517:Plant Roots / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation; D010738:Type C Phospholipases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D002118:Calcium; D004247:DNA; D010710:Phosphates; D010713:Phosphatidylcholines; D010743:Phospholipids; D010940:Plant Proteins; D010738:Type C Phospholipases; C000731236:AT3G03530 protein, Arabidopsis