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Dimerization and DNA binding facilitate alpha-helix formation of Max in solution
M Horiuchi1, Y Kurihara, M Katahira
1Department of Bioengineering, Faculty of Engineering, Yokohama National University.
Journal of Biochemistry
|December 17, 1997
Summary
The basic helix-loop-helix/leucine zipper (b/HLH/Z) protein Max110 increases its alpha-helical content and forms dimers upon increasing concentration or binding to DNA. This structural change is crucial for its function.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Max is a basic region/helix-loop-helix/leucine zipper (b/HLH/Z) protein involved in gene regulation.
- It forms complexes with Myc family proteins and binds to DNA sequences containing CACGTG.
- Understanding Max's structural properties is key to elucidating its biological functions.
Purpose of the Study:
- To investigate the structural properties of the N-terminal domain of Max (Max110) in aqueous solution.
- To determine how protein concentration affects the structure of Max110.
- To examine the impact of DNA binding on Max110 structure.
Main Methods:
- Circular dichroism (CD) spectroscopy to assess alpha-helical content.
- Sedimentation equilibrium experiments to determine protein oligomerization state.
- Characterization of a 109-amino-acid protein fragment (Max110).
Main Results:
- Alpha-helical content of Max110 increases with protein concentration.
- Max110 transitions from a monomer to a dimer as concentration increases.
- DNA binding, specifically to CACGTG sequences, further enhances the alpha-helical content of Max110.
Conclusions:
- Dimerization of Max110 is concentration-dependent.
- DNA binding promotes a more helical structure in Max110.
- Both dimerization and DNA interaction favor an increase in alpha-helical content, suggesting conformational changes are integral to Max's function.