title: Structural characterization of eRF1 mutants indicate a complex mechanism of stop codon recognition.
abstract: Eukarya translation termination requires the stop codon recognizing protein eRF1. In contrast to the multiple proteins required for translation termination in Bacteria, eRF1 retains the ability to recognize all three of the stop codons. The details of the mechanism that eRF1 uses to recognize stop codons has remained elusive. This study describes the structural effects of mutations in the eRF1 N-domain that have previously been shown to alter stop codon recognition specificity. Here, we propose a model of eRF1 binding to the pre-translation termination ribosomal complex that is based in part on our solution NMR structures of the wild-type and mutant eRF1 N-domains. Since structural perturbations induced by these mutations were spread throughout the protein structure, residual dipolar coupling (RDC) data were recorded to establish the long-range effects of the specific mutations, E55Q, Y125F, Q(122)FM(Y)F(126). RDCs were recorded on (15)N-labeled eRF1 N-domain weakly aligned in either 5% w/v n-octyl-penta (ethylene glycol)/octanol (C8E5) or the filamentous phage Pf1. These data indicate that the mutations alter the conformation and dynamics of the GTS loop that is distant from the mutation sites. We propose that the GTS loop forms a switch that is key for the multiple codon recognition capability of eRF1.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.
authors.forename: Shubhadra
authors.initials: S
authors.lastname: Pillay
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.
authors.forename: Leo E
authors.initials: LE
authors.lastname: Wong
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Pervushin
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D018388:Codon, Terminator; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000235:genetics; D000072417:Protein Domains; D017433:Protein Structure, Secondary
chemical_list: D018388:Codon, Terminator; C489002:ETF1 protein, human; D010454:Peptide Termination Factors