RNA structure replaces the need for U2AF2 in splicing.

Area of Science:

• Molecular Biology
• Genetics
• Evolutionary Biology

Background:

• RNA secondary structure is crucial for various RNA functions.
• Its role in messenger RNA (pre-mRNA) splicing has been less understood.
• Previous research has not widely recognized secondary structure's role in pre-mRNA splicing.

Purpose of the Study:

• To investigate the role of secondary structure in pre-mRNA splicing.
• To identify and characterize a novel class of introns dependent on secondary structure.
• To explore the evolutionary history and prevalence of this splicing mechanism.

Main Methods:

• Computational analysis of RNA sequences.
• Biochemical experiments to validate findings.
• Phylogenetic analysis to trace evolutionary origins.

Main Results:

• Identified a class of nuclear introns relying on secondary structure for splicing.
• These introns feature repeat expansions forming a bridging structure for splice site pairing.
• This mechanism bypasses the requirement for U2AF2, a key spliceosome component.
• Phylogenetic analysis indicates an ancient vertebrate origin for this splicing strategy.

Conclusions:

• A subset of nuclear introns utilizes RNA secondary structure for accurate splicing.
• This structure-based splicing mechanism predates tetrapod-teleost divergence.
• The mechanism is conserved in zebrafish, appearing in 10% of its genes, suggesting evolutionary persistence.
• This finding expands our understanding of RNA splicing diversity and evolution.