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Quaternary structure and function in phage lambda repressor: 1H-NMR studies of genetically altered proteins
M A Weiss1, M Karplus, R T Sauer
1Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge 02139.
Journal of Biomolecular Structure & Dynamics
|December 1, 1987
Summary
Phage lambda repressor
Area of Science:
- Molecular Biology
- Structural Biology
- Biophysics
Background:
- Phage lambda repressor controls gene expression.
- It has two domains: N-terminal for DNA binding and C-terminal for dimerization.
- The intact protein's structure and dynamics were previously unclear.
Purpose of the Study:
- To investigate the quaternary structure and dynamics of intact phage lambda repressor in solution.
- To understand the role of domain interactions in DNA binding.
- To elucidate the structural basis for operator recognition.
Main Methods:
- Proton Nuclear Magnetic Resonance (1H-NMR) spectroscopy.
- Proteolysis to separate protein domains.
- Analysis of protein structure and dynamics in solution.
Main Results:
- The N-terminal and C-terminal domains are loosely connected.
- Quaternary interactions between N-terminal domains were identified, involving helix 5.
- A mutation (Ile84Ser) disrupted these interactions, reducing DNA binding affinity.
Conclusions:
- Quaternary interactions between N-terminal domains are crucial for orienting the DNA-binding surface.
- These interactions are essential for high-affinity operator recognition.
- The study reveals key structural insights into phage lambda repressor function.