Molecular characterization of an Arabidopsis gene encoding a phospholipid-specific inositol polyphosphate 5-phosphatase.
Phosphoinositides are important molecules that serve as second messengers and bind to a complex array of proteins modulating their subcellular location and activity. The enzymes that metabolize phosphoinositides can in some cases serve to terminate the signaling actions of phosphoinositides. The inositol polyphosphate 5-phosphatases (5PTases) comprise a large protein family that hydrolyzes 5-phosphates from a variety of inositol phosphate and phosphoinositide substrates. We previously reported the identification of 15 putative 5PTase genes in Arabidopsis and have shown that overexpression of the At5PTase1 gene can alter abscisic acid signaling. At5PTase1 and At5PTase2 have been shown to hydrolyze the 5-phosphate from inositol phosphate substrates. We have examined the substrate specificity of the At5PTase11 protein, which is one of the smallest predicted 5PTases found in any organism. We report here that the At5PTase11 gene encodes an active 5PTase enzyme that can only dephosphorylate phosphoinositide substrates containing a 5-phosphate. In addition to hydrolyzing known substrates of 5PTase enzymes, At5PTase11 also hydrolyzes the 5-phosphate from phosphatidylinositol (3,5) bisphosphate. We also show that the At5PTase11 gene is regulated by abscisic acid, jasmonic acid, and auxin, suggesting a role for phosphoinositide action in these signal transduction pathways.
Ercetin
Mustafa E
ME
Department of Biochemistry and Fralin Biotechnology Center, Virginia Tech, Blacksburg, Virginia 24061, USA.
Gillaspy
Glenda E
GE
D000818:Animals; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004330:Drosophila / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D017422:Sequence Analysis, DNA; D000099182:Phosphoinositide 5-Phosphatases
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D010744:Phosphoric Monoester Hydrolases; D017853:Phosphotransferases (Alcohol Group Acceptor); D000099182:Phosphoinositide 5-Phosphatases; C068961:phosphatidylinositol 4,5-biphosphate kinase; C436286:5PTase1 protein, Arabidopsis; C488783:5PTase11 protein, Arabidopsis