title: Structure of the dual enzyme Ire1 reveals the basis for catalysis and regulation in nonconventional RNA splicing.
abstract: Ire1 is an ancient transmembrane sensor of ER stress with dual protein kinase and ribonuclease activities. In response to ER stress, Ire1 catalyzes the splicing of target mRNAs in a spliceosome-independent manner. We have determined the crystal structure of the dual catalytic region of Ire1at 2.4 A resolution, revealing the fusion of a domain, which we term the KEN domain, to the protein kinase domain. Dimerization of the kinase domain composes a large catalytic surface on the KEN domain which carries out ribonuclease function. We further show that signal induced trans-autophosphorylation of the kinase domain permits unfettered binding of nucleotide, which in turn promotes dimerization to compose the ribonuclease active site. Comparison of Ire1 to a topologically disparate ribonuclease reveals the convergent evolution of their catalytic mechanism. These findings provide a basis for understanding the mechanism of action of RNaseL and other pseudokinases, which represent 10% of the human kinome.
authors.affiliation: Program in Systems Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada.
authors.forename: Kenneth P K
authors.initials: KP
authors.lastname: Lee
authors.forename: Madhusudan
authors.initials: M
authors.lastname: Dey
authors.forename: Dante
authors.initials: D
authors.lastname: Neculai
authors.forename: Chune
authors.initials: C
authors.lastname: Cao
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dever
authors.forename: Frank
authors.initials: F
authors.lastname: Sicheri
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000502:physiology; D020134:Catalytic Domain / Q000502:physiology; D018360:Crystallography, X-Ray; D019281:Dimerization; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019143:Evolution, Molecular; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D010766:Phosphorylation; D010770:Phosphotransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D011487:Protein Conformation; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015003:Yeasts / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D009711:Nucleotides; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D010770:Phosphotransferases; C082863:IRE1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D012260:Ribonucleases