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Arm sequences contribute to the architecture and catalytic function of a lambda integrase-Holliday junction complex
Marta Radman-Livaja1, Christine Shaw, Marco Azaro
1Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Box G-J360, Providence, RI 02912, USA.
Molecular Cell
|April 2, 2003
Summary
Lambda integrase (Int) facilitates DNA recombination by bridging specific DNA sites. Arm sequences enhance Int
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Lambda integrase (Int) is essential for recombination between lambda phage and E. coli DNA.
- Accessory proteins and DNA looping are known to facilitate Int-mediated recombination.
- Recombination proceeds through a Holliday junction (HJ) intermediate.
Purpose of the Study:
- To investigate the role of arm sequences in lambda integrase (Int) catalytic activity.
- To elucidate the architecture of Int-DNA complexes during recombination.
- To understand how Int binds to both arm and core DNA sites.
Main Methods:
- Structural analysis of ternary complexes.
- Biochemical assays to assess catalytic activity.
- DNA binding studies.
Main Results:
- Arm sequences enhance the catalytic activity of the Int tetramer independently of accessory proteins.
- The architecture of ternary complexes containing HJ, Int, and arm DNA was determined.
- Int simultaneously binds to direct-repeat arm sites and indirect-repeat core sites.
Conclusions:
- Lambda integrase arm sequences play a direct role in facilitating recombination catalysis.
- The determined structures provide insights into higher-order recombinogenic complexes.
- Understanding these mechanisms can inform gene editing technologies.