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The intramolecular stem-loop structure of U6 snRNA can functionally replace the U6atac snRNA stem-loop.
1Department of Molecular Biology, Lerner Research Institute, Cleveland Clinic Foundation, Ohio 44195, USA.
RNA (New York, N.Y.)
|February 24, 2001
Summary
The U6atac snRNA stem-loop structure is crucial for U12-dependent splicing in vivo. Its function is analogous to the U6 snRNA stem-loop, highlighting conserved roles in spliceosome assembly.
Area of Science:
- Molecular Biology
- RNA Biology
- Genetics
Background:
- The U6 spliceosomal small nuclear RNA (snRNA) possesses an intramolecular stem-loop structure essential for spliceosome assembly and function.
- U6atac snRNA, the U12-dependent spliceosome analog, also features a conserved stem-loop structure between humans and plants.
Purpose of the Study:
- To investigate the functional analogy between U6 and U6atac snRNA stem-loops.
- To determine the structural and sequence requirements of the U6atac snRNA stem-loop for in vivo splicing.
Main Methods:
- Genetic suppression assays were employed using chimeric U6/U6atac snRNA constructs.
- Mutagenesis of the U6atac snRNA stem-loop, including disruption and compensatory mutations, was performed.
- In vivo splicing activity of wild-type and mutant constructs was assessed.
Main Results:
- Chimeric U6/U6atac snRNAs were active in vivo, supporting functional interchangeability.
- Mutations disrupting the U6atac stem-loop structure abolished splicing activity.
- Compensatory mutations restoring base pairing rescued splicing, but some mutants with retained base pairing potential remained inactive.
Conclusions:
- The U6atac snRNA stem-loop structure is essential for U12-dependent spliceosome function in vivo.
- The functional role of the U6atac snRNA stem-loop is likely analogous to that of the U6 snRNA stem-loop.
- Specific functional groups within the U6atac stem-loop may contribute to its role in splicing.