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Dynamics and DNA substrate recognition by the catalytic domain of lambda integrase
Srisunder Subramaniam1, Arun K Tewari, Simone E Nunes-Duby
1Biophysics Program, The Ohio State University, Columbus, OH 43210, USA.
Journal of Molecular Biology
|May 28, 2003
Summary
Bacteriophage lambda integrase (lambda-Int) uses a tyrosine residue for DNA cleavage. Studies show this tyrosine
Area of Science:
- Molecular Biology
- Enzymology
- Structural Biology
Background:
- Bacteriophage lambda integrase (lambda-Int) catalyzes site-specific DNA recombination.
- Cleavage involves a conserved tyrosine residue forming a covalent intermediate.
- Crystal structure of lambda-Int catalytic domain (C170) shows tyrosine distant from catalytic residues.
Purpose of the Study:
- Investigate conformational changes in lambda-Int upon DNA binding.
- Characterize the dynamics of the catalytic domain.
- Gain structural insights into C170/DNA complexes.
Main Methods:
- NMR spectroscopy
- Limited proteolysis
- Structural modeling based on Cre and Flp recombinases.
Main Results:
- The C-terminus of lambda-Int is flexible in the absence of DNA.
- Conformational changes in the tyrosine-containing beta-hairpin are not coupled to DNA binding.
- Models of C170/DNA complexes are consistent with experimental data and suggest trans complementation.
Conclusions:
- The study did not reveal the conformational change required for cis cleavage.
- Models provide insights into potential trans complementation mechanisms.
- Further structural studies are needed to fully elucidate the catalytic mechanism.