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Nucleolar maturation of the human small subunit processome.
Sameer Singh1, Arnaud Vanden Broeck1, Linamarie Miller1,2
1Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, NY 10065, USA.
Science (New York, N.Y.)
|September 13, 2021
Summary
The human small subunit processome guides ribosomal subunit maturation by linking RNA folding to cleavage. Cryo-EM structures reveal how this assembly coordinates RNA processing and degradation for efficient ribosome biogenesis.
Area of Science:
- Molecular Biology
- Structural Biology
- Cell Biology
Background:
- The small ribosomal subunit (SSU) is essential for protein synthesis.
- Ribosome biogenesis is a complex process involving numerous protein and RNA factors.
- The small subunit processome is a key player in the early stages of SSU maturation.
Purpose of the Study:
- To elucidate the molecular mechanisms of SSU processome maturation.
- To visualize the structural dynamics of the maturing human SSU processome.
- To understand how RNA folding is coupled to RNA processing and degradation.
Main Methods:
- High-resolution cryo-electron microscopy (cryo-EM).
- Structural analysis of maturing human SSU processomes.
- Biochemical assays to study RNA processing and degradation.
Main Results:
- Determined cryo-EM structures of human SSU processomes at 2.7–3.9 angstrom resolution.
- Revealed how RNA folding states are communicated to and coordinated with key enzymes.
- Identified mechanisms for exosome-mediated RNA degradation, endonucleolytic cleavage, and RNA unwinding.
Conclusions:
- The SSU processome exhibits remarkable structural plasticity, enabling coordinated RNA processing.
- Conserved mechanisms within the SSU processome ensure efficient and accurate SSU maturation.
- This nucleolar assembly plays a critical role in ribosome biogenesis from within the nucleolus.
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