title: Molecular Features of Phosphatase and Tensin Homolog (PTEN) Regulation by C-terminal Phosphorylation.
abstract: PTEN is a tumor suppressor that functions to negatively regulate the PI3K/AKT pathway as the lipid phosphatase for phosphatidylinositol 3,4,5-triphosphate. Phosphorylation of a cluster of Ser/Thr residues (amino acids 380-385) on the C-terminal tail serves to alter the conformational state of PTEN from an open active state to a closed inhibited state, resulting in a reduction of plasma membrane localization and inhibition of enzyme activity. The relative contribution of each phosphorylation site to PTEN autoinhibition and the structural basis for the conformational closure is still unclear. To further the structural understanding of PTEN regulation by C-terminal tail phosphorylation, we used protein semisynthesis to insert stoichiometric and site-specific phospho-Ser/Thr(s) in the C-terminal tail of PTEN. Additionally, we employed photo-cross-linking to map the intramolecular PTEN interactions of the phospho-tail. Systematic evaluation of the PTEN C-tail phospho-cluster showed autoinhibition, and conformational closure was influenced by the aggregate effect of multiple phospho-sites rather than dominated by a single phosphorylation site. Moreover, photo-cross-linking suggested a direct interaction between the PTEN C-tail and a segment in the N-terminal region of the catalytic domain. Mutagenesis experiments provided additional insights into how the PTEN phospho-tail interacts with both the C2 and catalytic domains.
authors.affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: Zan
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Dempsey
authors.affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: Stefani N
authors.initials: SN
authors.lastname: Thomas
authors.affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: Dawn
authors.initials: D
authors.lastname: Hayward
authors.affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205.
authors.forename: David M
authors.initials: DM
authors.lastname: Bolduc
authors.affiliation: Department of Pharmacology and Molecular Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205. Electronic address: pcole@jhmi.edu.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Cole
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D051059:PTEN Phosphohydrolase / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human
keywords: phosphatase; phosphatase and tensin homolog (PTEN); phosphorylation; post-translational modification (PTM); protein conformation; pten