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The Flp recombinase cleaves Holliday junctions in trans
J E Dixon1, A C Shaikh, P D Sadowski
1Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada.
Molecular Microbiology
|November 1, 1995
Summary
The Flp recombinase resolves complex DNA structures using a trans cleavage mechanism, where one protein molecule acts on another. This mechanism is crucial for both initial strand exchange and final resolution in Flp-mediated recombination.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Flp recombinase, from the 2 micrometers plasmid of Saccharomyces cerevisiae, is an integrase family member.
- Flp-mediated recombination involves two steps: formation of a Holliday-like intermediate and its resolution.
- Previous studies indicated Flp's active site involves two protomers and a trans cleavage mechanism for initial strand exchange.
Purpose of the Study:
- To investigate whether Flp resolves Holliday-like (chi) structures via the trans cleavage mechanism.
- To elucidate the mechanism of chi structure resolution by Flp recombinase.
Main Methods:
- In vitro complementation studies using mutant Flp proteins.
- Experiments utilizing nicked chi structures.
Main Results:
- Flp was shown to resolve chi structures through a trans cleavage mechanism.
- Evidence supports the involvement of trans cleavage in both initial strand exchange and resolution steps.
Conclusions:
- Flp recombinase resolves chi structures via trans cleavage.
- A model for Flp-mediated recombination incorporating trans cleavage at both stages of strand exchange is proposed.