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Structural basis for the second step of group II intron splicing
Russell T Chan1, Jessica K Peters1, Aaron R Robart1,2
1Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA.
Nature Communications
|November 10, 2018
Summary
This study reveals the crystal structure of a group II intron before the second splicing step. It shows how the intron
Area of Science:
- Molecular Biology
- Structural Biology
- Evolutionary Biology
Background:
- Group II introns and spliceosomes share structural and evolutionary links.
- Understanding intron splicing mechanisms is crucial for gene expression regulation.
Purpose of the Study:
- To elucidate the structural basis of the second step of group II intron splicing.
- To provide insights into the evolutionary relationship between group II introns and the spliceosome.
Main Methods:
- X-ray crystallography at 3.7 Å resolution.
- Analysis of a eukaryotic group II intron in the lariat-3' exon state.
Main Results:
- The crystal structure reveals the intact 3' splice site within the intron's catalytic core.
- The 5' exon's 3'-OH is positioned for nucleophilic attack and exon ligation.
- Conformational changes in the active site's catalytic triplex were observed before and after the second splicing step.
Conclusions:
- A model for the second step of group II intron splicing is proposed.
- A dynamic catalytic triplex is key for capturing the 3' splice site.
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