Selection of cryptic 5' splice sites by group II intron RNAs in vitro | JoVE Visualize

Selection of cryptic 5' splice sites by group II intron RNAs in vitro

¹Institut für Genetik und Mikrobiologie, Universität München, FRG.

Nucleic Acids Research|August 11, 1988

View abstract on PubMed

Summary

Group II introns recognize 5' splice sites through exon binding sequences (EBS) interacting with intron binding sites (IBS). This study shows EBS can pair with varied IBS, enabling new splice site selection mechanisms.

Area of Science:

Molecular Biology
RNA Splicing
Genetics

Background:

Group I and II self-splicing introns utilize specific RNA-RNA interactions for accurate splice site recognition.
Exon binding sequences (EBS) within the intron interact with complementary sequences in the exon near the 5' splice site.

Purpose of the Study:

To investigate the flexibility of exon binding sequences (EBS) in group II intron aI5c to recognize alternative intron binding sites (IBS).
To determine the minimal requirements for 5' splice site selection by group II introns.

Main Methods:

Mutagenesis of intron binding sites (IBS) and analysis of 5' splice site cleavage efficiency.
Testing of both cis- and trans-acting IBS elements with altered EBS sequences.
Deletion analysis of specific IBS elements to assess their role in splice site selection.

Main Results:

The exon binding sequences (EBS) of group II intron aI5c demonstrated tolerance for various substitutes of authentic intron binding sites (IBS).
Cleavage efficiency at cryptic 5' splice sites was enhanced by deleting the authentic IBS2 element.
The presence of an IBS1-like sequence preceding cryptic 5' cleavage sites indicated that IBS1/EBS1 pairing is sufficient for splice site selection.

Conclusions:

Group II intron splice site selection is not strictly dependent on perfectly matched endogenous IBS and EBS sequences.
IBS1/EBS1 pairing alone can direct the 5' cleavage reaction, highlighting the plasticity of intron-exon interactions.
Understanding these minimal requirements and positional effects provides insights into the evolution and mechanism of RNA splicing.