The Complete Structure of the Mycobacterium smegmatis 70S Ribosome

Cell Rep. 2017 Jul 5;20(1):149-160. doi: 10.1016/j.celrep.2017.06.029.


The ribosome carries out the synthesis of proteins in every living cell. It consequently represents a frontline target in anti-microbial therapy. Tuberculosis ranks among the leading causes of death worldwide, due in large part to the combination of difficult-to-treat latency and antibiotic resistance. Here, we present the 3.3-Å cryo-EM structure of the 70S ribosome of Mycobacterium smegmatis, a close relative to the human pathogen Mycobacterium tuberculosis. The structure reveals two additional ribosomal proteins and localizes them to the vicinity of drug-target sites in both the catalytic center and the decoding site of the ribosome. Furthermore, we visualized actinobacterium-specific rRNA and protein expansions that extensively remodel the ribosomal surface with implications for polysome organization. Our results provide a foundation for understanding the idiosyncrasies of mycobacterial translation and reveal atomic details of the structure that will facilitate the design of anti-tubercular therapeutics.

Keywords: Actinobacterium; Mycobacterium; antibiotic; cryo-EM; polysome; ribosome; translation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Cryoelectron Microscopy
  • Mycobacterium smegmatis / chemistry*
  • Mycobacterium smegmatis / ultrastructure
  • Protein Domains
  • RNA, Ribosomal / chemistry
  • Ribosomal Proteins / chemistry
  • Ribosome Subunits, Large, Bacterial / chemistry*
  • Ribosome Subunits, Large, Bacterial / ultrastructure


  • Bacterial Proteins
  • RNA, Ribosomal
  • Ribosomal Proteins