Crystal Structure of the Phosphatidylinositol 3,4-Bisphosphate-Binding Pleckstrin Homology (Ph) Domain of Tandem Ph-Domain-Containing Protein 1 (Tapp1): Molecular Basis of Lipid Specificity
Phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)] and its immediate breakdown product PtdIns(3,4)P(2) function as second messengers in growth factor- and insulin-induced signalling pathways. One of the ways that these 3-phosphoinositides a ...
Phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)] and its immediate breakdown product PtdIns(3,4)P(2) function as second messengers in growth factor- and insulin-induced signalling pathways. One of the ways that these 3-phosphoinositides are known to regulate downstream signalling events is by attracting proteins that possess specific PtdIns-binding pleckstrin homology (PH) domains to the plasma membrane. Many of these proteins, such as protein kinase B, phosphoinositide-dependent kinase 1 and the dual adaptor for phosphotyrosine and 3-phosphoinositides (DAPP1) interact with both PtdIns(3,4,5)P(3) and PtdIns(3,4)P(2) with similar affinity. Recently, a new PH-domain-containing protein, termed tandem PH-domain-containing protein (TAPP) 1, was described which is the first protein reported to bind PtdIns(3,4)P(2) specifically. Here we describe the crystal structure of the PtdIns(3,4)P(2)-binding PH domain of TAPP1 at 1.4 A (1 A=0.1 nm) resolution in complex with an ordered citrate molecule. The structure is similar to the known structure of the PH domain of DAPP1 around the D-3 and D-4 inositol-phosphate-binding sites. However, a glycine residue adjacent to the D-5 inositol-phosphate-binding site in DAPP1 is substituted for a larger alanine residue in TAPP1, which also induces a conformational change in the neighbouring residues. We show that mutation of this glycine to alanine in DAPP1 converts DAPP1 into a TAPP1-like PH domain that only interacts with PtdIns(3,4)P(2), whereas the alanine to glycine mutation in TAPP1 permits the TAPP1 PH domain to interact with PtdIns(3,4,5)P(3).
Related Citations:
Identification of Pleckstrin-Homology-Domain-Containing Proteins with Novel Phosphoinositide-Binding Specificities Dowler, S.,Currie, R.A.,Campbell, D.G.,Deak, M.,Kular, G.,Downes, C.P.,Alessi, D.R. (2000) Biochem.J. 351: 19
Structural Basis for Discrimination of 3-Phosphoinositides by Pleckstrin Homology Domains Ferguson, K.M.,Kavran, J.M.,Sankaran, V.G.,Fournier, E.,Isakoff, S.J.,Skolnik, E.Y.,Lemmon, M.A. (2000) Mol.Cell 6: 373
Organizational Affiliation:
Division of Biological Chemistry and Molecular Microbiology, Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK.
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