Related Experiment Videos
Amino-terminal arm of the lambda repressor: a 1H NMR study
Biochemistry
|October 23, 1984
Summary
The lambda repressor's N-terminal arm is flexible, aiding its binding to operator DNA. This flexibility is crucial for the repressor-operator complex model, allowing the arm to wrap around the DNA helix.
Area of Science:
- Molecular Biology
- Biophysics
- Structural Biology
Background:
- The lambda repressor protein controls the lysogenic cycle of bacteriophage lambda.
- Understanding the structural dynamics of the lambda repressor is key to elucidating its DNA binding mechanism.
Purpose of the Study:
- To investigate the flexibility of the N-terminal arm of the lambda repressor in solution.
- To determine the impact of N-terminal modifications on the operator-binding domain conformation.
Main Methods:
- Utilized one- and two-dimensional proton nuclear magnetic resonance (1H NMR) spectroscopy.
- Analyzed relaxation data of specific residues, such as Threonine-2 (Thr-2).
- Assessed conformational changes upon N-terminal residue deletion and point mutation (Lys-4 to Gln).
Main Results:
- Demonstrated significant flexibility of the lambda repressor's N-terminal arm in solution.
- Observed that Thr-2 relaxation is largely independent of overall macromolecular tumbling, indicating local motion.
- Found no alteration in the operator-binding domain's conformation after removing the first three residues or introducing the Lys-4----Gln mutation.
Conclusions:
- The N-terminal arm of the lambda repressor is conformationally flexible.
- This flexibility supports models where the N-terminal arm wraps around the DNA operator helix.
- Structural integrity of the operator-binding domain is maintained despite N-terminal modifications.