Visualizing the translation landscape in human cells at high resolution.

Area of Science:

• Structural biology
• Cellular biology
• Molecular mechanisms of protein synthesis

Background:

• Understanding macromolecular structures in their cellular context is crucial for biology and health.
• Previous studies often relied on purified components, limiting insights into native cellular environments.

Purpose of the Study:

• To achieve unprecedented detail of protein synthesis within human cells.
• To identify novel protein factors and structural states of the ribosome in situ.

Main Methods:

• Combined automated cryo-focused ion beam (FIB) milling with in situ single-particle cryo-electron microscopy (cryo-EM).
• Resolved high-resolution structures of the human 80S ribosome and its functional states.

Main Results:

• Achieved a 2.19 Å consensus structure of the human 80S ribosome with 21 distinct functional states.
• Identified previously uncharacterized ribosome-associated factors, including SERBP1, EDF1, and NAC/3.
• Discovered SERBP1 binding across multiple ribosome states, suggesting a regulatory role in translation.
• Visualized the interface between adjacent ribosomes forming helical polysomes.
• Resolved structures of ribosomes treated with drugs, revealing bound polyamines and drug interactions.

Conclusions:

• In situ cryo-EM provides unparalleled structural detail of protein synthesis in native cellular environments.
• The findings reveal novel regulatory mechanisms and interactions involving the ribosome.
• This approach advances structural studies within complex cellular contexts.