Detection of a sequence feature for recursive splicing

Area of Science:

• Molecular Biology
• Genetics
• RNA Processing

Background:

• RNA splicing removes introns from pre-mRNA to form mature mRNA.
• Recursive splicing is a mechanism where large introns are removed in segments by the spliceosome.
• The sequence elements governing recursive splicing have remained largely unidentified.

Purpose of the Study:

• To identify cis-acting sequence signals associated with recursive splicing.
• To investigate the influence of first introns on recursive splicing patterns.
• To develop a predictive model for recursive splicing.

Main Methods:

• Probabilistic mixture models were employed to analyze sequence data.
• Sequence features flanking the first intron were examined.
• A novel medium-throughput primer extension assay was utilized for validation.

Main Results:

• Recursive splicing is more frequent in longer, CG-rich first introns with specific flanking sequences.
• Depletion of CGs in the downstream polypyrimidine tract was observed.
• First intron sequence properties predict recursive splicing frequency in downstream introns.
• A sequence-dependent classifier for recursive splicing was developed and validated.

Conclusions:

• Newly identified sequence motifs at the beginning of RNA synthesis influence recursive splicing.
• Early RNA processing events, dictated by first intron sequences, affect subsequent splicing.
• The findings provide insights into the regulation of recursive splicing.