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Following Cell-fate in E. coli After Infection by Phage Lambda
Published on: October 14, 2011
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Interaction of int protein with specific sites on lambda att DNA
Cell
|October 1, 1979
Summary
Int protein binds to specific DNA sequences at the lambda phage attachment site (attP). These binding sites differ in location and interaction, particularly in the presence of heparin, influencing DNA recombination.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Site-specific recombination is crucial for viral integration and genome stability.
- The Int protein mediates recombination at the lambda phage attachment sites (attP and attB).
Purpose of the Study:
- To investigate the precise DNA binding sites of the Int protein within the lambda phage attP region.
- To characterize the differential interaction of Int protein with attP and attB DNA sequences, especially under inhibitory conditions.
Main Methods:
- DNAse I and neocarzinostatin partial digestion assays to identify Int protein-protected DNA regions.
- Competition assays using heparin to probe the stability and nature of Int-DNA interactions.
Main Results:
- Int protein protects two distinct DNA regions (30-35 bp each) within the attP site, including the common core and a distal P' arm site.
- These two attP binding sites exhibit differential sensitivity to heparin, with the distal site being more resistant.
- Int protein interaction with attB DNA differs, protecting a smaller 15 bp region at the left half of the common core in the absence of heparin, with no protection observed in its presence.
Conclusions:
- Int protein recognizes and binds to multiple, non-homologous sites at the attP attachment region.
- The differential binding affinities and heparin sensitivity of Int protein to attP sites suggest distinct roles in recombination.
- Int protein's interaction with attB is distinct from attP and is sensitive to heparin, highlighting regulatory mechanisms in lambda phage integration.
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