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The topological mechanism of phage lambda integrase.
N J Crisona1, R L Weinberg, B J Peter
1Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA.
Journal of Molecular Biology
|June 17, 1999
Summary
Bacteriophage lambda integrase (Int) mediates DNA recombination. This study reveals Int reactions are inherently chiral, producing specific product forms, and proposes a unified model for its diverse functions.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Bacteriophage lambda integrase (Int) is a key enzyme for phage DNA integration and excision.
- Its diverse recombination activities complicate understanding of the underlying reaction topology.
- Previous models struggled to unify the different Int-mediated reactions.
Purpose of the Study:
- To develop a unified topological model for all bacteriophage lambda integrase (Int) reactions.
- To elucidate the chirality and geometric underpinnings of Int recombination.
- To investigate the differences between integrative and excisive Int recombination.
Main Methods:
- Systematic analysis of Int reaction product topology.
- Application of mathematical tangle analysis.
- Comparison of Int with other related recombinases (Flp, Cre).
Main Results:
- All Int reactions exhibit intrinsic chirality, producing specific enantiomers.
- A unified model explains Int recombination, irrespective of DNA supercoiling.
- Excisive and integrative recombination differ by DNA crossings within the synaptic complex.
- Lambda Int's chirality is conserved in Flp and Cre recombinases.
Conclusions:
- The study provides a unified topological model for lambda integrase (Int) recombination.
- Chirality is a fundamental property of Int-mediated DNA manipulation.
- The model offers insights into the mechanism of site-specific recombination across different enzymes.