Structural snapshots of actively translating human ribosomes

Area of Science:

• Molecular Biology
• Structural Biology
• Biophysics

Background:

• Macromolecular machines like ribosomes undergo significant conformational changes.
• Molecular machines operate under thermodynamic control, with proteins fluctuating between states.
• Understanding these dynamics is key to deciphering protein synthesis.

Purpose of the Study:

• To visualize native translation intermediates of actively translating human ribosomes.
• To analyze ribosome-ligand interactions at high resolution.
• To identify static and dynamic elements crucial for ribosome function.

Main Methods:

• Cryo-electron microscopy (cryo-EM) of ex-vivo-derived human polysomes.
• Multiparticle refinement for high-resolution structural analysis.
• 3D variability analysis to capture dynamic states.

Main Results:

• Visualized diverse native translation intermediates, including elongation, decoding, and termination/recycling complexes.
• Identified significantly populated states of the ribosome during its functional cycle.
• Detailed ribosome-ligand interactions at the single-residue level in post-translocational states.

Conclusions:

• Human ribosomes exist in multiple, functionally relevant conformational states during translation.
• Cryo-EM and advanced analysis reveal intricate details of ribosome dynamics and interactions.
• This work provides a foundation for understanding the thermodynamics of molecular machines.