title: Substrate preference and phosphatidylinositol monophosphate inhibition of the catalytic domain of the Per-Arnt-Sim domain kinase PASKIN.
abstract: The Per-Arnt-Sim (PAS) domain serine/threonine kinase PASKIN, or PAS kinase, links energy flux and protein synthesis in yeast, regulates glycogen synthesis and protein translation in mammals, and might be involved in insulin regulation in the pancreas. According to the current model, binding of a putative ligand to the PAS domain disinhibits the kinase domain, leading to PASKIN autophosphorylation and increased kinase activity. To date, only synthetic but no endogenous PASKIN ligands have been reported. In the present study, we identified a number of novel PASKIN kinase targets, including ribosomal protein S6. Together with our previous identification of eukaryotic elongation factor 1A1, this suggests a role for PASKIN in the regulation of mammalian protein translation. When searching for endogenous PASKIN ligands, we found that various phospholipids can bind PASKIN and stimulate its autophosphorylation. Interestingly, the strongest binding and autophosphorylation was achieved with monophosphorylated phosphatidylinositols. However, stimulated PASKIN autophosphorylation did not correlate with ribosomal protein S6 and eukaryotic elongation factor 1A1 target phosphorylation. Although autophosphorylation was enhanced by monophosphorylated phosphatidylinositols, di- and tri-phosphorylated phosphatidylinositols inhibited autophosphorylation. By contrast, target phosphorylation was always inhibited, with the highest efficiency for di- and tri-phosphorylated phosphatidylinositols. Because phosphatidylinositol monophosphates were found to interact with the kinase rather than with the PAS domain, these data suggest a multiligand regulation of PASKIN activity, including a still unknown PAS domain binding/activating ligand and kinase domain binding modulatory phosphatidylinositol phosphates.
authors.affiliation: Institute of Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Philipp
authors.initials: P
authors.lastname: Schläfli
authors.forename: Juliane
authors.initials: J
authors.lastname: Tröger
authors.forename: Katrin
authors.initials: K
authors.lastname: Eckhardt
authors.forename: Emanuela
authors.initials: E
authors.lastname: Borter
authors.forename: Patrick
authors.initials: P
authors.lastname: Spielmann
authors.forename: Roland H
authors.initials: RH
authors.lastname: Wenger
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D007328:Insulin / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D038601:Ribosomal Protein S6 / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D007328:Insulin; D018129:Phosphatidylinositol Phosphates; D038601:Ribosomal Protein S6; C116037:PAS domain kinases; D017346:Protein Serine-Threonine Kinases