Structure of transfer RNAs: similarity and variability

Abstract

Transfer RNAs (tRNAs) are ancient molecules whose origin goes back to the beginning of life on Earth. Key partners in the ribosome-translation machinery, tRNAs read genetic information on messenger RNA and deliver codon specified amino acids attached to their distal 3'-extremity for peptide bond synthesis on the ribosome. In addition to this universal function, tRNAs participate in a wealth of other biological processes and undergo intricate maturation events. Our understanding of tRNA biology has been mainly phenomenological, but ongoing progress in structural biology is giving a robust physico-chemical basis that explains many facets of tRNA functions. Advanced sequence analysis of tRNA genes and their RNA transcripts have uncovered rules that underly tRNA 2D folding and 3D L-shaped architecture, as well as provided clues about their evolution. The increasing number of X-ray structures of free, protein- and ribosome-bound tRNA, reveal structural details accounting for the identity of the 22 tRNA families (one for each proteinogenic amino acid) and for the multifunctionality of a given family. Importantly, the structural role of post-transcriptional tRNA modifications is being deciphered. On the other hand, the plasticity of tRNA structure during function has been illustrated using a variety of technical approaches that allow dynamical insights. The large range of structural properties not only allows tRNAs to be the key actors of translation, but also sustain a diversity of unrelated functions from which only a few have already been pinpointed. Many surprises can still be expected.

Mechanistic Studies Reveal Similar Catalytic Strategies for Phosphodiester Bond Hydrolysis by Protein-only and RNA-dependent Ribonuclease P

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“…In consequence, their sequence is under three strong functional constraints. First, tRNAs require similar overall structures to participate equivalently in translation (Kim et al 1974;Westhof et al 1985;Basavappa and Sigler 1991;Giege et al 2012). Second, tRNAs require unique features to ensure specific charging by cognate synthetases and accurately decode mRNA, both of which often require specific modifications (Putz et al 1994;Giege et al 1998;Murphy et al 2004;Agris et al 2007) and elements outside the anti-codon (Musier-Forsyth et al 1991;Cochella and Green 2005;Ledoux et al 2009;Ling et al 2009;Shepotinovskaya and Uhlenbeck 2013).…”