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Multidegenerate DNA recognition by the OxyR transcriptional regulator
L A Tartaglia1, C J Gimeno, G Storz
1Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
The Journal of Biological Chemistry
|January 25, 1992
Summary
The Escherichia coli OxyR protein specifically binds to its DNA targets in both active and inactive states. This binding relies on a unique "degenerate recognition code" to identify varied DNA sequences.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The Escherichia coli OxyR protein regulates genes induced by hydrogen peroxide.
- OxyR's transcriptional activity depends on its oxidized (active) or reduced (inactive) state.
Purpose of the Study:
- To investigate the DNA-binding specificity and recognition mechanism of the OxyR protein.
- To understand how OxyR recognizes diverse DNA sequences despite limited conservation.
Main Methods:
- Purification of OxyR protein in its oxidized form.
- DNA-binding affinity assays comparing OxyR binding to functional sites versus random DNA.
- Sequence alignment of OxyR-binding sites.
- Methylation interference assays to map OxyR-DNA contacts.
Main Results:
- OxyR exhibits high binding specificity for its functional DNA sites in both oxidized and reduced forms.
- OxyR-binding sites show degenerate homology, lacking perfectly conserved positions.
- OxyR primarily contacts degenerate homology positions within its recognition sequences.
Conclusions:
- The OxyR protein utilizes a multidegenerate recognition code to bind seemingly dissimilar DNA sequences.
- This degenerate recognition system allows OxyR to bind its targets even in the absence of oxidative stress.