title: Phosphorylation-mediated PTEN conformational closure and deactivation revealed with protein semisynthesis.
abstract: The tumor suppressor PIP3 phosphatase PTEN is phosphorylated on four clustered Ser/Thr on its C-terminal tail (aa 380-385) and these phosphorylations are proposed to induce a reduction in PTEN's plasma membrane recruitment. How these phosphorylations affect the structure and enzymatic function of PTEN is poorly understood. To gain insight into the mechanistic basis of PTEN regulation by phosphorylation, we generated semisynthetic site-specifically tetra-phosphorylated PTEN using expressed protein ligation. By employing a combination of biophysical and enzymatic approaches, we have found that purified tail-phosphorylated PTEN relative to its unphosphorylated counterpart shows reduced catalytic activity and membrane affinity and undergoes conformational compaction likely involving an intramolecular interaction between its C-tail and the C2 domain. Our results suggest that there is a competition between membrane phospholipids and PTEN phospho-tail for binding to the C2 domain. These findings reveal a key aspect of PTEN's regulation and suggest pharmacologic approaches for direct PTEN activation. DOI:http://dx.doi.org/10.7554/eLife.00691.001.
authors.affiliation: Department of Pharmacology and Molecular Sciences , Johns Hopkins University School of Medicine , Baltimore , United States.
authors.forename: David
authors.initials: D
authors.lastname: Bolduc
authors.forename: Meghdad
authors.initials: M
authors.lastname: Rahdar
authors.forename: Becky
authors.initials: B
authors.lastname: Tu-Sekine
authors.forename: Sindhu Carmen
authors.initials: SC
authors.lastname: Sivakumaren
authors.forename: Daniel
authors.initials: D
authors.lastname: Raben
authors.forename: L Mario
authors.initials: LM
authors.lastname: Amzel
authors.forename: Peter
authors.initials: P
authors.lastname: Devreotes
authors.forename: Sandra B
authors.initials: SB
authors.lastname: Gabelli
authors.forename: Philip
authors.initials: P
authors.lastname: Cole
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000595:Amino Acid Sequence; D002852:Chromatography, Ion Exchange; D008969:Molecular Sequence Data; D051059:PTEN Phosphohydrolase / Q000737:chemistry*; D010766:Phosphorylation; D011487:Protein Conformation; D059748:Proteolysis; D053838:Scattering, Small Angle
chemical_list: D000469:Alkaline Phosphatase; D051059:PTEN Phosphohydrolase
keywords: Human; cancer; lipid phosphatase; protein