- A novel class of PTEN protein in Arabidopsis displays unusual phosphoinositide phosphatase activity and efficiently binds phosphatidic acid
- Biochemical Journal
- Volume | Issue number
- 441 | 1
- Pages (from-to)
- Document type
- Faculty of Science (FNWI)
- Swammerdam Institute for Life Sciences (SILS)
PTEN proteins are dual phosphatases with both protein and phosphoinositide phosphatase activity. They modulate signaling pathways controlling growth, metabolism and apoptosis in animals and are implied in several human diseases. We describe here a novel class of PTEN proteins in plants, termed PTEN2, which comprises the AtPTEN2a 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, PI(3,4)P2, and PI(3,5)P2. In contrast to the animal PTENs, the PI(3,4,5)P3 is a poor substrate. Site-directed mutagenesis of AtPTEN2a and molecular modeling of protein-phosphoinositide interactions indicated that substitutions at the PTEN2 core catalytic site of the K267 and G268 residues found in animals, and which are critical for animal PTEN activity, by the M267 and A268 residues found in the eudicot PTEN2 are responsible for changes in substrate specificity. Remarkably, the AtPTEN2a protein also displays strong binding activity for phosphatidic acid (PA), a major lipid second messenger in plants. Promoter::GUS fusion, transcript and protein analyses further showed the transcriptional regulation of the ubiquitously expressed AtPTEN2a and AtPTEN2b by salt and osmotic stress. The data suggests a function for this novel class of plant PTEN as an effector of lipid signaling in plants.
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