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Flexibility in DNA recombination: structure of the lambda integrase catalytic core
H J Kwon1, R Tirumalai, A Landy
1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston MA 02115, USA.
Science (New York, N.Y.)
|April 4, 1997
Summary
Lambda integrase, a site-specific recombinase, performs DNA rearrangements via a phosphotyrosine intermediate. Its conserved protein fold and bipartite active site explain its DNA cleavage mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Lambda integrase is a key enzyme in site-specific recombination, facilitating DNA rearrangements.
- It operates without external energy input, utilizing a covalent phosphotyrosine intermediate.
Purpose of the Study:
- To elucidate the structural basis of lambda integrase's catalytic activity.
- To understand the mechanism of DNA cleavage and strand exchange.
Main Methods:
- Determined the 1.9 angstrom crystal structure of the integrase catalytic domain.
- Analyzed the protein fold and active site residues.
Main Results:
- Revealed a conserved protein fold across diverse organisms (archaebacteria to yeast).
- Identified a bipartite active site with a flexible loop containing Tyr342 and a basic groove.
- The structure suggests a model for target DNA interaction.
Conclusions:
- The bipartite active site explains the enzyme's ability to perform both cis and trans DNA cleavage.
- The conserved structure highlights evolutionary conservation of this recombination mechanism.