title: Structural and Functional Analysis of the Allosteric Inhibition of IRE1α with ATP-Competitive Ligands.
abstract: The accumulation of unfolded proteins under endoplasmic reticulum (ER) stress leads to the activation of the multidomain protein sensor IRE1α as part of the unfolded protein response (UPR). Clustering of IRE1α lumenal domains in the presence of unfolded proteins promotes kinase trans-autophosphorylation in the cytosol and subsequent RNase domain activation. Interestingly, there is an allosteric relationship between the kinase and RNase domains of IRE1α, which allows ATP-competitive inhibitors to modulate the activity of the RNase domain. Here, we use kinase inhibitors to study how ATP-binding site conformation affects the activity of the RNase domain of IRE1α. We find that diverse ATP-competitive inhibitors of IRE1α promote dimerization and activation of RNase activity despite blocking kinase autophosphorylation. In contrast, a subset of ATP-competitive ligands, which we call KIRAs, allosterically inactivate the RNase domain through the kinase domain by stabilizing monomeric IRE1α. Further insight into how ATP-competitive inhibitors are able to divergently modulate the RNase domain through the kinase domain was gained by obtaining the first structure of apo human IRE1α in the RNase active back-to-back dimer conformation. Comparison of this structure with other existing structures of IRE1α and integration of our extensive structure activity relationship (SAR) data has led us to formulate a model to rationalize how ATP-binding site ligands are able to control the IRE1α oligomeric state and subsequent RNase domain activity.
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington, United States.
authors.forename: Hannah C
authors.initials: HC
authors.lastname: Feldman
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University Medical School , Stony Brook, New York, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Tong
authors.affiliation: Department of Medicine, University of California-San Francisco , San Francisco, California, United States.|Diabetes Center, University of California-San Francisco , San Francisco, California, United States.|Lung Biology Center, University of California-San Francisco , San Francisco, California, United States.|California Institute for Quantitative Biosciences, University of California-San Francisco , San Francisco, California, United States.
authors.forename: Likun
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Medicine, University of California-San Francisco , San Francisco, California, United States.|Diabetes Center, University of California-San Francisco , San Francisco, California, United States.|Lung Biology Center, University of California-San Francisco , San Francisco, California, United States.|California Institute for Quantitative Biosciences, University of California-San Francisco , San Francisco, California, United States.
authors.forename: Rosa
authors.initials: R
authors.lastname: Meza-Acevedo
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington, United States.
authors.forename: Theodore A
authors.initials: TA
authors.lastname: Gobillot
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University Medical School , Stony Brook, New York, United States.
authors.forename: Ivan
authors.initials: I
authors.lastname: Lebedev
authors.affiliation: Department of Medicine, University of California-San Francisco , San Francisco, California, United States.|Lung Biology Center, University of California-San Francisco , San Francisco, California, United States.
authors.forename: Micah J
authors.initials: MJ
authors.lastname: Gliedt
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington, United States.
authors.forename: Sanjay B
authors.initials: SB
authors.lastname: Hari
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington, United States.
authors.forename: Arinjay K
authors.initials: AK
authors.lastname: Mitra
authors.affiliation: Department of Medicine, University of California-San Francisco , San Francisco, California, United States.|Lung Biology Center, University of California-San Francisco , San Francisco, California, United States.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Backes
authors.affiliation: Department of Medicine, University of California-San Francisco , San Francisco, California, United States.|Diabetes Center, University of California-San Francisco , San Francisco, California, United States.|Lung Biology Center, University of California-San Francisco , San Francisco, California, United States.|California Institute for Quantitative Biosciences, University of California-San Francisco , San Francisco, California, United States.
authors.forename: Feroz R
authors.initials: FR
authors.lastname: Papa
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University Medical School , Stony Brook, New York, United States.
authors.forename: Markus A
authors.initials: MA
authors.lastname: Seeliger
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington, United States.|Department of Biochemistry, University of Washington , Seattle, Washington, United States.
authors.forename: Dustin J
authors.initials: DJ
authors.lastname: Maly
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000494:Allosteric Regulation; D001667:Binding, Competitive; D059865:Endoplasmic Reticulum Stress; D004722:Endoribonucleases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D015394:Molecular Structure; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D012260:Ribonucleases / Q000037:antagonists & inhibitors; D013329:Structure-Activity Relationship
chemical_list: D008024:Ligands; D047428:Protein Kinase Inhibitors; D000255:Adenosine Triphosphate; C528229:ERN1 protein, human; D017346:Protein Serine-Threonine Kinases; D004722:Endoribonucleases; D012260:Ribonucleases