Ribosomal proteins S12 and S13 function as control elements for translocation of the mRNA:tRNA complex

Mol Cell. 2003 Aug;12(2):321-8. doi: 10.1016/s1097-2765(03)00275-2.


Translocation of the mRNA:tRNA complex through the ribosome is promoted by elongation factor G (EF-G) during the translation cycle. Previous studies established that modification of ribosomal proteins with thiol-specific reagents promotes this event in the absence of EF-G. Here we identify two small subunit interface proteins S12 and S13 that are essential for maintenance of a pretranslocation state. Omission of these proteins using in vitro reconstitution procedures yields ribosomal particles that translate in the absence of enzymatic factors. Conversely, replacement of cysteine residues in these two proteins yields ribosomal particles that are refractive to stimulation with thiol-modifying reagents. These data support a model where S12 and S13 function as control elements for the more ancient rRNA- and tRNA-driven movements of translocation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biological Transport
  • Cysteine / chemistry
  • Escherichia coli / metabolism
  • Escherichia coli Proteins
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Peptide Elongation Factor G / metabolism
  • Phenylalanine / chemistry
  • Protein Binding
  • Protein Structure, Secondary
  • RNA, Messenger / metabolism*
  • RNA, Transfer / metabolism*
  • Recombinant Proteins / metabolism
  • Ribosomal Proteins / chemistry*
  • Time Factors


  • Escherichia coli Proteins
  • Peptide Elongation Factor G
  • RNA, Messenger
  • Recombinant Proteins
  • Ribosomal Proteins
  • ribosomal protein S12
  • ribosomal protein S30
  • rpsM protein, E coli
  • Phenylalanine
  • RNA, Transfer
  • Cysteine