title: Structural insight into the recognition of amino-acylated initiator tRNA by eIF5B in the 80S initiation complex.
abstract: BACKGROUND
  From bacteria to eukarya, the specific recognition of the amino-acylated initiator tRNA by the universally conserved translational GTPase eIF5B/IF2 is one of the most central interactions in the process of translation initiation. However, the molecular details, particularly also in the context of ribosomal initiation complexes, are only partially understood.
  
  
  RESULTS
  A reinterpretation of the 6.6 Å resolution cryo-electron microscopy (cryo-EM) structure of the eukaryal 80S initiation complex using the recently published crystal structure of eIF5B reveals that domain IV of eIF5B forms extensive interaction interfaces with the Met-tRNAi, which, in contrast to the previous model, directly involve the methionylated 3' CCA-end of the acceptor stem. These contacts are mediated by a conserved surface area, which is homologous to the surface areas mediating the interactions between IF2 and fMet-tRNAfMet as well as between domain II of EF-Tu and amino-acylated elongator tRNAs.
  
  
  CONCLUSIONS
  The reported observations provide novel direct structural insight into the specific recognition of the methionylated acceptor stem by eIF5B domain IV and demonstrate its universality among eIF5B/IF2 orthologs in the three domains of life.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kuhle
authors.forename: Ralf
authors.initials: R
authors.lastname: Ficner
mesh_terms: D001105:Archaea / Q000737:chemistry; D001665:Binding Sites; D002597:Chaetomium / Q000737:chemistry; D020285:Cryoelectron Microscopy; D039642:Eukaryotic Initiation Factors / Q000737:chemistry* / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry
chemical_list: D039642:Eukaryotic Initiation Factors; D005656:Fungal Proteins; C451459:eukaryotic initiation factor-5B; D012343:RNA, Transfer; D008715:Methionine