Blasticidin S inhibits translation by trapping deformed tRNA on the ribosome

Proc Natl Acad Sci U S A. 2013 Jul 23;110(30):12283-8. doi: 10.1073/pnas.1304922110. Epub 2013 Jul 3.


The antibiotic blasticidin S (BlaS) is a potent inhibitor of protein synthesis in bacteria and eukaryotes. We have determined a 3.4-Å crystal structure of BlaS bound to a 70S⋅tRNA ribosome complex and performed biochemical and single-molecule FRET experiments to determine the mechanism of action of the antibiotic. We find that BlaS enhances tRNA binding to the P site of the large ribosomal subunit and slows down spontaneous intersubunit rotation in pretranslocation ribosomes. However, the antibiotic has negligible effect on elongation factor G catalyzed translocation of tRNA and mRNA. The crystal structure of the antibiotic-ribosome complex reveals that BlaS impedes protein synthesis through a unique mechanism by bending the 3' terminus of the P-site tRNA toward the A site of the large ribosomal subunit. Biochemical experiments demonstrate that stabilization of the deformed conformation of the P-site tRNA by BlaS strongly inhibits peptidyl-tRNA hydrolysis by release factors and, to a lesser extent, peptide bond formation.

Keywords: peptidyl transfer; ribosome crystal structure; termination inhibitor; translation inhibitor; translation termination.

Publication types

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

MeSH terms

  • Crystallography, X-Ray
  • Fluorescence Resonance Energy Transfer
  • Models, Molecular
  • Nucleosides / pharmacology
  • Protein Biosynthesis / drug effects*
  • RNA, Transfer / chemistry
  • RNA, Transfer / metabolism*
  • Ribosomes / metabolism*
  • Thermus thermophilus / metabolism


  • Nucleosides
  • blasticidin S
  • RNA, Transfer

Associated data

  • PDB/4L6J
  • PDB/4L6K
  • PDB/4L6L