Transfer RNA in the hybrid P/E state: correlating molecular dynamics simulations with cryo-EM data

Proc Natl Acad Sci U S A. 2007 Oct 16;104(42):16540-5. doi: 10.1073/pnas.0708094104. Epub 2007 Oct 9.

Abstract

Transfer RNA (tRNA) transiently occupies the hybrid P/E state (P/E-tRNA) when mRNA-tRNA are translocated in the ribosome. In this study, we characterize the structure of P/E-tRNA and its interactions with the ribosome by correlating the results from molecular dynamics simulations on free tRNA with the cryo-EM map of P/E-tRNA. In our approach, we show that the cryo-EM map may be interpreted as a conformational average. Along the molecular dynamics trajectories (44 ns, 18 ns, and 18 ns), some of the snapshots prove to be quite close to the observed density. In a representative structure, the CCA (3') arm is uniquely twisted, and the anticodon stem loop is kinked at the junctions to both the anticodon loop and the D stem. In addition, the map shows that the P/E-tRNA is no longer bound to helix H69 of 23S rRNA and is flexible, and the conformations of helices H68 and h44 of 16S rRNA differ from those in the x-ray structure. Thus, our study presents structural and dynamic information on the P/E-tRNA and characterizes its interactions with the translocating ribosome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cryoelectron Microscopy
  • Nucleic Acid Conformation
  • RNA, Messenger / chemistry
  • RNA, Ribosomal, 23S / chemistry
  • RNA, Transfer / chemistry*
  • Ribosomes / chemistry*

Substances

  • RNA, Messenger
  • RNA, Ribosomal, 23S
  • RNA, Transfer

Associated data

  • PDB/2Z9Q