Visualizing translation dynamics at atomic detail inside a bacterial cell.

Area of Science:

• Structural Biology
• Molecular Biology
• Microbiology

Background:

• Translation is a fundamental cellular process, essential for protein synthesis, catalyzed by ribosomes.
• Understanding ribosome dynamics in vivo is crucial for deciphering cellular mechanisms and developing targeted therapies.

Purpose of the Study:

• To visualize the structural dynamics of translation within the bacterium Mycoplasma pneumoniae at high resolution.
• To animate translation elongation and investigate polysome formation and coordination in native cellular environments.

Main Methods:

• Utilized cryo-electron tomography and sub-tomogram analysis for in-cell structural visualization.
• Obtained high-resolution in-cell average maps of translating ribosomes and built an atomic model.
• Classified distinct ribosome states and mapped intracellular polysome organization.

Main Results:

• Resolved 13 distinct ribosome states, recapitulating known in vitro states and reflecting active translation intermediates.
• Animated translation elongation within native cells, demonstrating the impact of antibiotics on cellular translation.
• Identified a local coordination mechanism for polysome association mediated by ribosomal protein L9.

Conclusions:

• The study demonstrates the feasibility of visualizing molecular processes, like translation, at atomic detail within living cells.
• The findings provide insights into translation fidelity, polysome organization, and the effects of antibiotics on bacterial translation.