Sequence of U1 RNA from Drosophila melanogaster: implications for U1 secondary structure and possible involvement in...

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• U1 small nuclear ribonucleoproteins (snRNPs) are crucial for pre-mRNA splicing in eukaryotes.
• Understanding the evolutionary conservation of U1 RNA provides insights into the fundamental mechanisms of gene expression.

Purpose of the Study:

• To identify and characterize U1 RNA in Drosophila melanogaster.
• To compare the sequence and potential secondary structure of Drosophila U1 RNA with its vertebrate counterparts.
• To investigate the role of conserved and divergent regions in U1 RNA-hnRNA interactions during splicing.

Main Methods:

• Identification of U1 RNA using anti-(U1)RNP antibodies from human lupus patients.
• RNA sequencing for direct analysis of the U1 RNA molecule.
• DNA sequencing of a genomic clone isolated by hybridization to Drosophila U1 RNA.
• Comparative sequence analysis with human and vertebrate U1 RNA sequences.

Main Results:

• Drosophila U1 RNA was identified and its sequence determined, showing 72% agreement with human U1 RNA.
• Nucleotides essential for binding to donor splice junctions (5') are exactly conserved.
• Divergence was observed in nucleotides postulated to interact with acceptor splice junctions (3').
• Comparative analysis favored a specific secondary structure model for U1 RNA.

Conclusions:

• The findings support the hypothesis that U1 snRNPs are involved in RNA splicing across species.
• Specific modifications to the splicing model are suggested, highlighting conserved and divergent molecular interactions between U1 RNA and hnRNA.
• This study provides a molecular basis for understanding the evolution of the splicing machinery.