title: Selectivity of stop codon recognition in translation termination is modulated by multiple conformations of GTS loop in eRF1.
abstract: Translation termination in eukaryotes is catalyzed by two release factors eRF1 and eRF3 in a cooperative manner. The precise mechanism of stop codon discrimination by eRF1 remains obscure, hindering drug development targeting aberrations at translation termination. By solving the solution structures of the wild-type N-domain of human eRF1 exhibited omnipotent specificity, i.e. recognition of all three stop codons, and its unipotent mutant with UGA-only specificity, we found the conserved GTS loop adopting alternate conformations. We propose that structural variability in the GTS loop may underline the switching between omnipotency and unipotency of eRF1, implying the direct access of the GTS loop to the stop codon. To explore such feasibility, we positioned N-domain in a pre-termination ribosomal complex using the binding interface between N-domain and model RNA oligonucleotides mimicking Helix 44 of 18S rRNA. NMR analysis revealed that those duplex RNA containing 2-nt internal loops interact specifically with helix α1 of N-domain, and displace C-domain from a non-covalent complex of N-domain and C-domain, suggesting domain rearrangement in eRF1 that accompanies N-domain accommodation into the ribosomal A site.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
authors.forename: Leo E
authors.initials: LE
authors.lastname: Wong
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Shubhadra
authors.initials: S
authors.lastname: Pillay
authors.forename: Ludmila
authors.initials: L
authors.lastname: Frolova
authors.forename: Konstantin
authors.initials: K
authors.lastname: Pervushin
mesh_terms: D001665:Binding Sites; D018388:Codon, Terminator; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry / Q000378:metabolism
chemical_list: D018388:Codon, Terminator; C489002:ETF1 protein, human; D010454:Peptide Termination Factors; D012313:RNA