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. WIREs RNA 2012, 3:37–61. doi: 10.1002/wrna.103 This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Processing > tRNA Processing