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Transposon-mediated site-specific recombination: a defined in vitro system.
Cell
|September 1, 1981
Summary
The study demonstrates that purified resolvase protein can catalyze the site-specific recombination required for gamma delta (γδ) transposition in vitro. This in vitro system, using resolvase and supercoiled DNA, bypasses the need for host factors or cofactors for cointegrate resolution.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Transposition of the gamma delta (γδ) element involves intermediate cointegrate structures.
- These structures are resolved into final transposition products via site-specific recombination at the res sequence.
- Resolvase, a protein encoded by the γδ element, is essential for this resolution process.
Purpose of the Study:
- To establish and characterize an in vitro system for studying the site-specific recombination involved in γδ transposition resolution.
- To investigate the minimal requirements for the resolvase-mediated resolution reaction.
Main Methods:
- Purified resolvase protein was used with a cointegrate analog substrate.
- Reactions were performed in vitro using negatively supercoiled substrate DNA, buffer, and magnesium ions (Mg2+).
- Reaction products were analyzed to determine the outcome of the resolution process under different conditions.
Main Results:
- Site-specific recombination and cointegrate resolution were successfully demonstrated in vitro.
- The reaction minimally requires resolvase, supercoiled DNA, buffer, and Mg2+.
- Catenated, resolved molecules were identified as the major products.
- Absence of Mg2+ led to altered product formation.
Conclusions:
- An efficient in vitro system for studying γδ transposition resolution has been developed.
- The resolution reaction is independent of host factors and high-energy cofactors.
- This system provides a valuable tool for detailed mechanistic studies of site-specific recombination mediated by resolvase.