Architecture of the yeast small subunit processome

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The small subunit (SSU) processome is a crucial ribonucleoprotein complex essential for eukaryotic ribosome biogenesis.
• It coordinates the folding, cleavage, and modification of pre-ribosomal RNA (rRNA) to form the small ribosomal subunit.

Purpose of the Study:

• To determine the high-resolution structure of the yeast SSU processome.
• To elucidate the molecular mechanisms underlying eukaryotic ribosome assembly.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was employed to determine the structure.
• High-resolution structural analysis at 5.1-angstrom resolution.

Main Results:

• The structure reveals how the SSU processome, along with 5' external transcribed spacer and U3 small nucleolar RNA, forms an RNA-protein assembly platform.
• This platform facilitates the coordinated maturation of 18S rRNA domains.
• A central molecular motor suggests a mechanism for conformational changes within the complex.

Conclusions:

• The study provides a detailed structural framework for understanding eukaryotic ribosome assembly in Saccharomyces cerevisiae.
• The findings offer insights into the intricate coordination of RNA processing and protein interactions during ribosome biogenesis.