18S rRNA processing requires the RNA helicase-like protein Rrp3

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Ribosomal RNA (rRNA) processing is a fundamental cellular process for protein synthesis.
• DEAD box proteins are a large family involved in RNA metabolism, including transcription and translation.
• Previous studies identified yeast DEAD box proteins involved in rRNA assembly, but their specific roles in 18S rRNA maturation were unclear.

Purpose of the Study:

• To identify and characterize novel genes involved in pre-ribosomal RNA (pre-rRNA) processing.
• To elucidate the specific role of the newly identified RRP3 gene in rRNA maturation.
• To investigate the biochemical properties of the RRP3 protein.

Main Methods:

• Polymerase Chain Reaction (PCR) screening for DEAD box genes.
• Genetic analysis of RRP3-depleted yeast strains.
• Protein purification and biochemical assays (RNA-dependent ATPase activity).

Main Results:

• Identification of RRP3, a gene encoding a 60.9 kDa protein essential for pre-rRNA processing.
• RRP3 is specifically required for the maturation of 18S rRNA from the 35S primary transcript.
• Depletion of RRP3 leads to aberrant cleavage of 35S pre-rRNA, with cleavage occurring between sites A2 and B1 instead of A0, A1, and A2.
• Purified Rrp3 protein exhibits weak, non-specific RNA-dependent ATPase activity.

Conclusions:

• RRP3 is a novel DEAD box protein critical for 18S rRNA maturation in yeast.
• This finding expands the known functions of DEAD box proteins in rRNA biogenesis.
• RRP3 represents a key component in the pathway of ribosome synthesis, specifically for the production of the 18S rRNA subunit.