Specific alterations of U1-C protein or U1 small nuclear RNA can eliminate the requirement of Prp28p, an essential...

Area of Science:

• Molecular Biology
• RNA Biology
• Protein Function

Background:

• The in vivo roles of DExD/H box proteins, including RNA helicases, are largely unknown.
• Essential DEAD box proteins like Prp28p play critical roles in cellular processes.

Purpose of the Study:

• To investigate the in vivo function of the DEAD box protein Prp28p.
• To elucidate the mechanism by which Prp28p interacts with U1 small nuclear RNA (snRNA) and U1-C protein during splicing.

Main Methods:

• Genetic analysis using mutations in U1-C protein and U1 snRNA.
• Biochemical assays to study RNA-RNA duplex stabilization and dissociation.

Main Results:

• Prp28p's essential function can be bypassed by specific mutations in U1-C or U1 snRNA.
• The L13 residue of U1-C stabilizes the U1 snRNA/5' splice site duplex.
• Prp28p antagonizes U1-C's stabilizing effect, promoting U1 ribonucleoprotein dissociation.

Conclusions:

• Prp28p counteracts U1-C protein to regulate U1 snRNP dissociation from the 5' splice site.
• DExD/H box proteins may mediate RNA-RNA rearrangements by antagonizing RNA-stabilizing proteins, beyond simple unwinding.