NAR’s Breakthrough Articles present high-impact studies answering long-standing questions in the field of nucleic acids research and/or opening up new areas and mechanistic hypotheses for investigation. These articles are chosen by the Editors on the recommendation of Editorial Board Members and Referees. Articles are accompanied by a brief synopsis explaining the findings of the paper and where they fit in the broader context of nucleic acids research. They represent the very best papers published at NAR.
Designer tRNAs for efficient incorporation of non-canonical amino acids by the pyrrolysine system in mammalian cells
The study describes the generation of two novel suppressor tRNAs that boost the efficiency of the pyrrolysine system for the genetic incorporation of non-canonical amino acids (ncAAs) into proteins in mammalian cells. The new tRNAs extend the repertoire of chemical tools generally applicable to study biological processes in the live mammalian cell. The archaeal (Pyl)/tRNAPyl pair is a commonly used system for the incorporation of...
Incorporation of non-natural amino acids into a nascent peptide is a challenging problem. Incorporation of a consecutive sequence of D-amino acids in vitro translation (FIT) systems usually results in low yields and proline has been shown to form peptide bonds slower than other amino acid. Elongation Factor P (EF-P) is a translation factor that stimulates peptide bond formation between proline residues through interactions with the D-arm on tRNAPro. The authors reasoned that if a D-amino acid were charged to a tRNA that is optimized for interactions with EF-Tu and EF-P, then EF-P could enhance incorporation of consecutive D-amino acids. They employed in vitro translation assays with tRNAPro1 and chimeric tRNAs. Maximum D-amino acid incorporation was achieved with EF-P and a tRNA that contained a tRNAPro1 D-arm to facilitate EF-P interaction and a tRNAGluE2 T-stem to enhance EFTu binding. The paper provides a thorough characterization of EF-P stimulated D-amino acid incorporation.
DNA-assisted oligomerization of pore-forming toxin monomers into precisely-controlled protein channels
This article describes a novel approach to control oligomerization of α-hemolysin monomers into functional nanopores with enlarged diameters compared to the naturally occurring α-hemolysin pore. Biological pores show promise as ultra-sensitive sensor elements for the rapid and label-free analysis of single molecules. This has been demonstrated by the wide-range of applications of these pores, which include DNA sequencing, studies of protein folding, disease diagnosis, and drug screening. A challenge in nanopore sensing is controlling the geometrical and chemical properties of the channels. In this study, investigators designed well-defined DNA nanostructures that are based on a single-stranded circular DNA molecule with dimensions that match those of the targeted pore. Protein binding sites along the DNA template allow for the attachment of α-hemolysin monomers.