title: Lipid regulators of Pkh2 in Candida albicans, the protein kinase ortholog of mammalian PDK1.
abstract: Pkh is the yeast ortholog of the mammalian 3-phosphoinositide-dependent protein kinase 1 (PDK1). Pkh phosphorylates the activation loop of Ypks, Tpks, Sch9 and also phosphorylates the eisosome components Lsp1 and Pil1, which play fundamental roles upstream of diverse signaling pathways, including the cell wall integrity and sphingosine/long-chain base (LCB) signaling pathways. In S. cerevisiae, two isoforms, ScPkh1 and ScPkh2, are required for cell viability, while only one ortholog exists in C. albicans, CaPkh2. In spite of the extensive information gathered on the role of Pkh in the LCB signaling, the yeast Pkh kinases are not known to bind lipids and previous studies did not identify PH domains in Pkh sequences. We now describe that the C-terminal region of CaPkh2 is required for its intrinsic kinase activity. In addition, we found that the C-terminal region of CaPkh2 enables its interaction with structural and signaling lipids. Our results further show that phosphatidylserine, phosphatidic acid, phosphatidylinositol (3,4 and 4,5)-biphosphates, and phosphatidylinositol (3,4,5)-trisphosphate inhibit Pkh activity, whereas sulfatide binds with high affinity but does not affect the intrinsic activity of CaPkh2. Interestingly, we identified that its human ortholog PDK1 also binds to sulfatide. We propose a mechanism by which lipids and dihydrosphingosine regulate CaPkh2 kinase activity by modulating the interaction of the C-terminal region with the kinase domain, while sulfatide-like lipids support localization CaPkh2 mediated by a C-terminal PH domain, without affecting kinase intrinsic activity.
authors.affiliation: Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pastor-Flores
authors.affiliation: Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors.forename: Jörg O
authors.initials: JO
authors.lastname: Schulze
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain; Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Bahí
authors.affiliation: Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Süß
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain; Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain. Electronic address: antonio.casamayor@uab.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Casamayor
authors.affiliation: Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany. Electronic address: biondi@med.uni-frankfurt.de.
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Biondi
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D002176:Candida albicans / Q000201:enzymology* / Q000235:genetics; D019295:Computational Biology; D005656:Fungal Proteins / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D050356:Lipid Metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010712:Phosphatidic Acids / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D013329:Structure-Activity Relationship; D013433:Sulfoglycosphingolipids / Q000378:metabolism; D014162:Transfection
chemical_list: D005656:Fungal Proteins; D010712:Phosphatidic Acids; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010718:Phosphatidylserines; D013433:Sulfoglycosphingolipids; C060974:phosphatidylinositol 3,4,5-triphosphate; C060980:phosphatidylinositol 3,4-diphosphate; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578562:PDPK1 protein, human; D013110:Sphingosine; C005682:safingol
keywords: Allostery; Budding yeast; C. albicans; Cell wall integrity; DHS; PDK1; PHS; PI(3,4)P(2); PI(3,4,5)P(3); PI(4,5)P(2); PIP(3); Phosphatidic acid; Phosphatidylcholine; Phosphatidylethanolamine; Phosphatidylserine; Pkh; Sphingosine; Sulfatide