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A LexA mutant repressor with a relaxed inter-domain linker
P Oertel-Buchheit1, J Reinbolt, M John
1Institut de Biologie Moléculaire et Cellulaire, UPR 9002 du CNRS, Strasbourg, France.
Protein Science : a Publication of the Protein Society
|April 1, 1998
Summary
The LexA protein
Area of Science:
- Molecular Biology
- Protein Structure
- Biochemistry
Background:
- LexA protein belongs to prokaryotic transcriptional repressors.
- It has DNA binding and dimerization domains separated by a hinge region.
- The hinge region is widely considered flexible and unconstrained.
Purpose of the Study:
- To investigate the structural flexibility of the LexA protein's hinge region.
- To challenge the prevailing hypothesis of a fully flexible inter-domain linker.
Main Methods:
- Utilized a mutant LexA repressor with point mutations in the hinge region.
- Assessed protease sensitivity (trypsin and Glu-C) of the wild-type and mutant LexA hinge regions.
Main Results:
- Mutant LexA hinge region showed sensitivity to protease cleavage over a 20-amino acid segment.
- Wild-type LexA hinge region demonstrated resistance to the same proteases.
- These findings contradict the notion of a completely flexible linker.
Conclusions:
- The LexA hinge region is not entirely flexible and is likely constrained.
- Constrained structure may result from interactions with the carboxy-terminal domain or intrinsic local stability.