AtPIP5K1, an Arabidopsis thaliana phosphatidylinositol phosphate kinase, synthesizes PtdIns(3,4)P(2) and PtdIns(4,5)P(2) in vitro and is inhibited by phosphorylation.
PtdIns phosphate kinases (PIPkins), which generate PtdInsP(2) isomers, have been classified into three subfamilies that differ in their substrate specificities. We demonstrate here that the previously identified AtPIP5K1 gene from Arabidopsis thaliana encodes a PIPkin with dual substrate specificity in vitro, capable of phosphorylating PtdIns3P and PtdIns4P to PtdIns(3,4)P(2) and PtdIns(4,5)P(2) respectively. We also show that recombinant AtPIP5K1 is phosphorylated by protein kinase A and a soluble protein kinase from A. thaliana. Phosphorylation of AtPIP5K1 by protein kinase A is accompanied by a 40% inhibition of its catalytic activity. Full activity is recovered by treating phosphorylated AtPIP5K1 with alkaline phosphatase.
Westergren
T
T
Department of Plant Biochemistry, Lund University, PO Box 124, SE-221 00 Lund, Sweden.
Dove
S K
SK
Sommarin
M
M
Pical
C
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002458:Cell Fractionation; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D017930:Genes, Reporter / Q000235:genetics; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000096:biosynthesis*; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D011993:Recombinant Fusion Proteins; C060980:phosphatidylinositol 3,4-diphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D017868:Cyclic AMP-Dependent Protein Kinases