The real-time path of translation factor IF3 onto and off the ribosome

Mol Cell. 2007 Jan 26;25(2):285-96. doi: 10.1016/j.molcel.2006.12.011.

Abstract

Translation initiation factor IF3 is an essential bacterial protein, consisting of two domains (IF3C and IF3N) separated by a linker, which interferes with ribosomal subunit association, promotes codon-anticodon interaction in the P site, and ensures translation initiation fidelity. Using time-resolved chemical probing, we followed the dynamic binding path of IF3 on the 30S subunit and its release upon 30S-50S association. During binding, IF3 first contacts the platform (near G700) of the 30S subunit with the C domain and then the P-decoding region (near A790) with its N domain. At equilibrium, attained within less than a second, both sites are protected, but before reaching binding equilibrium, IF3 causes additional transient perturbations of both the platform edge and the solvent side of the subunit. Upon 30S-50S association, IF3 dissociates concomitantly with the establishment of the 30S-50S bridges, following the reverse path of its binding with the IF3N-A790 interaction being lost before the IF3C-G700 interaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Binding Sites
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Prokaryotic Initiation Factor-3 / chemistry*
  • Prokaryotic Initiation Factor-3 / genetics
  • Prokaryotic Initiation Factor-3 / metabolism*
  • Protein Structure, Tertiary
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / genetics
  • RNA, Bacterial / metabolism
  • RNA, Ribosomal, 16S / chemistry
  • RNA, Ribosomal, 16S / genetics
  • RNA, Ribosomal, 16S / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Ribosomes / chemistry
  • Ribosomes / metabolism*

Substances

  • Escherichia coli Proteins
  • Prokaryotic Initiation Factor-3
  • RNA, Bacterial
  • RNA, Ribosomal, 16S
  • Recombinant Proteins