title: A novel class of PTEN protein in Arabidopsis displays unusual phosphoinositide phosphatase activity and efficiently binds phosphatidic acid.
abstract: PTEN (phosphatase and tensin homologue deleted on chromosome ten) proteins are dual phosphatases with both protein and phosphoinositide phosphatase activity. They modulate signalling pathways controlling growth, metabolism and apoptosis in animals and are implied in several human diseases. In the present paper we describe a novel class of PTEN pro-teins in plants, termed PTEN2, which comprises the AtPTEN (Arabidopsis PTEN) 2a and AtPTEN2b proteins in Arabidopsis. Both display low in vitro tyrosine phosphatase activity. In addition, AtPTEN2a actively dephosphorylates in vitro the 3' phosphate group of PI3P (phosphatidylinositol 3-phosphate), PI(3,4)P2 (phosphatidylinositol 3,4-bisphosphate) and PI(3,5)P2 (phosphatidylinositol 3,5-bisphosphate). In contrast with animal PTENs, PI(3,4,5)P3 (phosphatidylinositol 3,4,5-trisphosphate) is a poor substrate. Site-directed mutagenesis of AtPTEN2a and molecular modelling of protein-phosphoinositide interactions indicated that substitutions at the PTEN2 core catalytic site of the Lys267 and Gly268 residues found in animals, which are critical for animal PTEN activity, by Met267 and Ala268 found in the eudicot PTEN2 are responsible for changes in substrate specificity. Remarkably, the AtPTEN2a protein also displays strong binding activity for PA (phosphatidic acid), a major lipid second messenger in plants. Promoter::GUS (β-glucuronidase) fusion, transcript and protein analyses further showed the transcriptional regulation of the ubiquitously expressed AtPTEN2a and AtPTEN2b by salt and osmotic stress. The results of the present study suggest a function for this novel class of plant PTEN proteins as an effector of lipid signalling in plants.
authors.affiliation: INRA, Biologie du Fruit et Pathologie, UMR 1332, Université de Bordeaux, BP 81, 33883 Villenave d'Ornon cedex, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Pribat
authors.forename: Rodnay
authors.initials: R
authors.lastname: Sormani
authors.forename: Mathieu
authors.initials: M
authors.lastname: Rousseau-Gueutin
authors.forename: Magdalena M
authors.initials: MM
authors.lastname: Julkowska
authors.forename: Christa
authors.initials: C
authors.lastname: Testerink
authors.forename: Jerôme
authors.initials: J
authors.lastname: Joubès
authors.forename: Michel
authors.initials: M
authors.lastname: Castroviejo
authors.forename: Michel
authors.initials: M
authors.lastname: Laguerre
authors.forename: Christian
authors.initials: C
authors.lastname: Meyer
authors.forename: Véronique
authors.initials: V
authors.lastname: Germain
authors.forename: Christophe
authors.initials: C
authors.lastname: Rothan
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D008958:Models, Molecular; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D015398:Signal Transduction; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D010712:Phosphatidic Acids; C570039:PTEN2a protein, Arabidopsis; C570040:PTEN2b protein, Arabidopsis; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase