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Kinetic studies of Fos.Jun.DNA complex formation: DNA binding prior to dimerization.
1Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA.
Biochemistry
|January 5, 2001
Summary
The Fos and Jun proteins form a complex to activate transcription. DNA binding enhances their dimerization, with sequential monomer binding to DNA being the favored pathway for complex assembly.
Area of Science:
- Molecular biology
- Biochemistry
- Genetics
Background:
- The bZIP proteins Fos and Jun form a high-affinity heteromeric complex crucial for mediating activated transcription.
- Understanding the kinetic assembly pathway of these protein-DNA complexes is essential for elucidating transcriptional regulation mechanisms.
Purpose of the Study:
- To investigate the kinetic pathway of Fos.Jun.DNA complex assembly using stopped-flow fluorescence resonance energy transfer (FRET).
- To determine the influence of DNA on the dimerization rate of Fos and Jun proteins.
Main Methods:
- Stopped-flow fluorescence resonance energy transfer (FRET) was employed to monitor the kinetics of complex formation.
- Global kinetic analysis was used to determine the favored assembly pathway.
Main Results:
- Dimerization of Fos and Jun occurs rapidly, but this rate is further enhanced in the presence of DNA.
- The study identified a favored pathway where individual Fos and Jun monomers bind DNA sequentially, assembling their dimerization interface post-DNA binding.
Conclusions:
- The assembly of Fos.Jun.DNA complexes involves a sequential DNA binding mechanism, with dimerization occurring on the DNA template.
- This pathway is critical for efficient and high-affinity binding, facilitating activated transcription.