Exon ligation is proofread by the DExD/H-box ATPase Prp22p

Area of Science:

• Molecular Biology
• RNA Splicing
• Gene Expression

Background:

• The spliceosome is crucial for messenger RNA (mRNA) production, removing introns from precursor mRNA (pre-mRNA).
• Spliceosome fidelity mechanisms that prevent aberrant intron splicing are not fully understood.
• Conserved DExD/H-box ATPases play roles in RNA processing, including splicing.

Purpose of the Study:

• To investigate the mechanisms by which the spliceosome ensures fidelity during mRNA splicing.
• To determine the role of the DExD/H-box ATPase Prp22p in spliceosome fidelity.
• To elucidate the function of Prp22p in repressing the formation of aberrant mRNA.

Main Methods:

• Investigated the effect of mutations in intronic consensus sequences on mRNA formation.
• Utilized mutations in the ATPase and RNA unwindase activities of Prp22p.
• Employed cold-sensitive prp22 mutants to assess aberrant mRNA formation in vivo.

Main Results:

• An ATP-dependent activity was identified that represses mRNA formation from aberrant splicing intermediates.
• Mutations impairing Prp22p's ATPase or RNA unwindase activity abolished this proofreading function.
• Aberrant mRNA was formed in vivo using cold-sensitive prp22 mutants with a mutated 3' splice site.

Conclusions:

• Prp22p possesses a dual function: repressing aberrant splicing intermediates and promoting genuine mRNA release.
• This dual role of Prp22p enhances spliceosome fidelity.
• DExD/H-box ATPases can generally enhance fidelity in RNA processing pathways.