Rei1 and Reh1 facilitate the loading of eL24.

Area of Science:

• Molecular Biology
• Cell Biology
• Ribosome Biogenesis

Background:

• Ribosome assembly is vital for cell viability and gene expression.
• Eukaryotic pre-ribosomal subunits are assembled in the nucleolus and cytoplasm.
• Cytoplasmic maturation involves loading specific ribosomal proteins, including eL24.

Purpose of the Study:

• To elucidate the unknown function of yeast proteins Rei1 and Reh1 in ribosome biogenesis.
• To investigate the role of Rei1 and Reh1 in the cytoplasmic loading of ribosomal protein eL24.

Main Methods:

• Analysis of pre-60S subunits from yeast cells lacking Rei1 and Reh1 (rei1Δ reh1Δ).
• Genetic screening for bypass suppressors of the rei1Δ reh1Δ growth defect.
• Assessing the impact of mutations in ribosomal protein uL3, GTPase Lsg1, and phosphatase Ppq1.

Main Results:

• Pre-60S subunits from rei1Δ reh1Δ cells showed a specific defect in eL24 loading.
• Overexpression of eL24 rescued the growth defect of the double mutant.
• Mutations in uL3, Lsg1, and Ppq1 partially restored eL24 loading in rei1Δ reh1Δ cells.

Conclusions:

• Rei1 and Reh1 facilitate the recruitment of ribosomal protein eL24 to the pre-60S particle.
• A revised model places Rei1 and Reh1 function in the cytoplasmic recruitment of eL24.
• This study clarifies a critical step in cytoplasmic ribosome biogenesis.