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Binding sites for bacteriophage HP1 integrase on its DNA substrates
1Department of Biochemistry, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205.
The Journal of Biological Chemistry
|August 19, 1994
Summary
The HP1 integrase binds specific DNA sequences to integrate its genome into Haemophilus influenzae. Two distinct binding site types, I and II, reveal how integrase interacts with attachment sites for recombination.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Temperate phage HP1 integrates into Haemophilus influenzae via site-specific recombination.
- This process involves specific DNA sequences known as attachment sites.
- HP1 integrase facilitates this integration reaction.
Purpose of the Study:
- To characterize the interactions between HP1 integrase and its DNA substrates.
- To identify and define the binding sites and consensus sequences for HP1 integrase.
- To understand the structural basis of DNA recognition and binding by integrase.
Main Methods:
- DNase I footprinting was employed to map integrase binding sites on DNA.
- Analysis of DNA cleavage patterns revealed protection and enhancement regions.
- DNA sequence analysis identified consensus motifs for binding sites.
Main Results:
- Two classes of integrase binding sites, type I and type II, were identified.
- Type I sites showed complete protection from DNase I cleavage, with consensus 5'-AGGGATTTWW.
- Type II sites exhibited alternating protection and enhancement, suggesting DNA distortion, with consensus 5'-ACTGGCGRTW.
Conclusions:
- HP1 integrase recognizes specific DNA sequences at attachment sites for integration.
- The distinct binding characteristics of type I and type II sites contribute to the integration mechanism.
- The arrangement of binding sites on attB and attP reflects their roles in site-specific recombination.