Coupling between snoRNP assembly and 3' processing controls box C/D snoRNA biosynthesis in yeast

Area of Science:

• Molecular Biology
• RNA Biology
• Gene Expression

Background:

• RNA polymerase II transcribes protein-coding genes and small stable RNAs.
• Small RNAs use polyadenylation-independent pathways for 3'-end formation, unlike pre-mRNA.
• Yeast snRNA and snoRNA 3'-end formation involves APT complex and independent factors like Nrd1p, Nab3p, and Sen1p.

Purpose of the Study:

• To investigate the role of box D mutations and Nop1p in box C/D snoRNA transcription and 3'-end formation.
• To elucidate the association of Nop1p with box C/D snoRNA genes and its interaction with APT components.
• To propose a quality control mechanism for snoRNA biogenesis.

Main Methods:

• Site-directed mutagenesis of conserved box D in snoRNAs.
• Analysis of Nop1p association with box C/D snoRNA genes.
• Co-immunoprecipitation assays to study interactions between Nop1p and APT components.
• Assessment of transcription and 3'-end formation in yeast mutants.

Main Results:

• Mutations in box D of snoRNAs and in Nop1p disrupt transcription and 3'-end formation of box C/D snoRNAs.
• Nop1p was found to associate with box C/D snoRNA genes.
• Nop1p interacts with components of the APT complex.
• Efficient transcription and 3'-end processing are dependent on the successful assembly of nascent snoRNAs into functional particles.

Conclusions:

• Nop1p plays a critical role in the quality control of box C/D snoRNA biogenesis.
• Successful assembly into small nucleolar ribonucleoprotein (snoRNP) particles is essential for efficient snoRNA transcription and 3'-end formation.
• This mechanism ensures the production of functional small RNAs.