title: Analysis of phosphoinositide binding domain properties within the myotubularin-related protein MTMR3.
abstract: The myotubularins are a large family of phosphoinositide-specific phosphatases with substrate specificity for PtdIns3P and PtdIns(3,5)P(2). In addition to an N-terminal PH-GRAM (PH-G) domain and a signature catalytic domain shared with other family members, MTMR3 contains a C-terminal FYVE domain. We show that the FYVE domain of MTMR3 is atypical in that it neither confers endosomal localisation nor binds to the lipid PtdIns3P. Furthermore the FYVE domain is not required for in vitro enzyme activity of MTMR3. In contrast, the PH-GRAM domain is able to bind to phosphoinositide lipids, of which the allosteric regulator PtdIns5P is the preferred partner. Consequently, generation of PtdIns5P at the plasma membrane by ectopic expression of the bacterial phosphatase IpgD leads to a translocation of MTMR3 that requires the PH-G domain. Deletion of the PH-G domain leads to loss of activity of MTMR3 in vitro, and surprisingly, when combined with an active site mutation, accumulates the protein on the Golgi complex.
authors.affiliation: Physiological Laboratory, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK.
authors.forename: Oscar
authors.initials: O
authors.lastname: Lorenzo
authors.forename: Sylvie
authors.initials: S
authors.lastname: Urbé
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Clague
mesh_terms: D000495:Allosteric Site; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D017353:Gene Deletion; D016678:Genome; D005982:Glutathione Transferase / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006836:Hydro-Lyases / Q000378:metabolism; D007313:Insecta; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009154:Mutation; D016366:Open Reading Frames; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry; D010716:Phosphatidylinositols / Q000737:chemistry*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry*; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D008055:Lipids; D008081:Liposomes; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; C106336:phosphatidylinositol 3,5-diphosphate; C055525:phosphatidylinositol 3-phosphate; D005982:Glutathione Transferase; D010744:Phosphoric Monoester Hydrolases; C444436:MTMR3 protein, human; D017027:Protein Tyrosine Phosphatases; D054558:Protein Tyrosine Phosphatases, Non-Receptor; C099588:myotubularin; D006836:Hydro-Lyases; C021434:imidazoleglycerolphosphate dehydratase