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Spectroscopic characterization of PTEN/PIP2 interaction
Author(s) -
Gericke Arne,
Redfern Roberta E,
Redfern Duane,
Munson Mary,
Ross Alonzo H
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a483-b
Subject(s) - pten , popc , conformational change , chemistry , phosphatase , vesicle , c2 domain , pi , lipid raft , biophysics , bodipy , phosphorylation , biochemistry , fluorescence , signal transduction , membrane , biology , pi3k/akt/mtor pathway , physics , quantum mechanics
PTEN, a phosphatase that dephosphorylates the 3′ position of phosphoinositides, is a tumor suppressor. Activation of PTEN by PI‐4,5‐P 2 requires a polybasic region at the N‐terminus. It was hypothesized that PI‐4,5‐P 2 aids membrane recruiting and induces a conformational change in PTEN. To test this hypothesis we have investigated the interaction of PTEN and a truncated PTEN lacking the N‐terminal polybasic region with PI‐4,5‐P 2 /POPC mixed vesicles by infrared spectroscopy. PI‐4,5‐P 2 induces a conformational change in PTEN towards more α‐helical content, but not for the truncated PTEN. The structural changes induced for PI‐4,5‐P 2 were greater than those for other anionic lipids, e.g., PS and PI‐4P. To further explore this conformational change, we have investigated the interaction of various peptides derived from the N‐terminus of PTEN with different phosphoinositides. It was found by fluorescence quenching experiments of mixed POPC/Bodipy PI‐4,5‐P 2 vesicles that PTEN 1–16 induces PI‐4,5‐P 2 domain formation. PI‐4,5‐P 2 induced domain formation more potently than other anionic lipids. Since it was suggested that the PI 3‐kinase/Akt pathway involves lipid rafts, we have investigated the effect of cholesterol on the PTEN‐induced PI‐4,5‐P 2 domain formation. It was found that the presence of cholesterol enhances the PTEN 1–16 /PI‐4,5‐P 2 interaction, resulting in a more pronounced segregation of PI‐4,5‐P 2 .