Structure of the dual enzyme Ire1 reveals the basis for catalysis and regulation in nonconventional RNA splicing

Cell. 2008 Jan 11;132(1):89-100. doi: 10.1016/j.cell.2007.10.057.

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.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / genetics*
  • Amino Acid Sequence
  • Binding Sites / physiology
  • Catalytic Domain / physiology
  • Crystallography, X-Ray
  • Dimerization
  • Endoplasmic Reticulum / metabolism
  • Evolution, Molecular
  • Membrane Glycoproteins / chemistry*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Nucleotides / chemistry
  • Nucleotides / metabolism
  • Oxidative Stress / physiology
  • Phosphorylation
  • Phosphotransferases / chemistry*
  • Phosphotransferases / genetics
  • Phosphotransferases / metabolism
  • Protein Binding / physiology
  • Protein Conformation
  • Protein Folding
  • Protein Structure, Tertiary / physiology
  • Protein-Serine-Threonine Kinases / chemistry*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Ribonucleases / chemistry*
  • Ribonucleases / genetics
  • Ribonucleases / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Yeasts / chemistry*
  • Yeasts / genetics
  • Yeasts / metabolism

Substances

  • Membrane Glycoproteins
  • Nucleotides
  • RNA, Messenger
  • Saccharomyces cerevisiae Proteins
  • Phosphotransferases
  • IRE1 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases
  • Ribonucleases

Associated data

  • PDB/2RIO