title: The three-dimensional arcitecture of the EJC core.
abstract: The exon junction complex (EJC) is a macromolecular complex deposited at splice junctions on mRNAs as a consequence of splicing. At the core of the EJC are four proteins: eIF4AIII, a member of the DExH/D-box family of NTP-dependent RNA binding proteins, Y14, Magoh, and MLN51. These proteins form a stable heterotetramer that remains bound to the mRNA throughout many different cellular environments. We have determined the three-dimensional (3D) structure of this EJC core using negative-stain random-conical tilt electron microscopy. This structure represents the first structure of a DExH/D-box protein in complex with its binding partners. The EJC core is a four-lobed complex with a central channel and dimensions consistent with its known RNA footprint of about ten nucleotides. Using known X-ray crystallographic structures and a model of three of the four components, we propose a model for complex assembly on RNA and explain how Y14:Magoh may influence eIF4AIII's RNA binding.
authors.affiliation: Howard Hughes Medical Institute, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
authors.forename: M Elizabeth
authors.initials: ME
authors.lastname: Stroupe
authors.forename: Thomas Ø
authors.initials: TØ
authors.lastname: Tange
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Thomas
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Moore
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Grigorieff
mesh_terms: D018360:Crystallography, X-Ray; D039601:Eukaryotic Initiation Factor-4A / Q000737:chemistry / Q000378:metabolism; D005091:Exons; D015870:Gene Expression; D006801:Humans; D008958:Models, Molecular; D016624:Negative Staining; D009363:Neoplasm Proteins / Q000737:chemistry / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000737:chemistry / Q000648:ultrastructure; D011485:Protein Binding; D022821:RNA Splice Sites; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: C459802:CASC3 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D022821:RNA Splice Sites; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D039601:Eukaryotic Initiation Factor-4A