NMR study of eukaryotic translation termination.

Abstract

Translation termination is critical. Many diseases are caused by nonsense mutation. Hence, understanding termination could pave the way to strategic interference of the process with medical benefit. Unlike in bacteria, eukaryotic translation termination is more complex. Exact mechanism of stop codon recognition by class I release factor eRF1 and the cooperative role of class II release factor eRF3 remain obscure. By solving the solution structures of both wild-type N-domain of human eRF1 exhibiting omnipotent specificity and its mutant with UGA-unipotency, 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. In addition, we showed the specific binding of a 15-mer RNA oligonucleotide mimicking the decoding region of 18S rRNA helix 44 to helix α1 of N-domain, on the interface that is shielded partially by C-domain in full-length eRF1. The 15-mer RNA displaces C-domain from the non-covalent NC-complex, suggesting an imperative domain rearrangement in eRF1 during which N-domain accommodates itself into ribosomal A site. On another hand, we also demonstrated the feasibility of targeted acquisition of NMR data that is dynamically controlled by the completeness of automatic backbone resonances assignment, in an effort to accelerate structural study of biomolecules by NMR spectroscopy.