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Products of the fos and jun proto-oncogenes bind cooperatively to the AP1 DNA recognition sequence

G Risse1, M Neuberg, J B Hunter

  • 1Institute of Molecular Biology and Tumor Research, Philipps University of Marburg, Federal Republic of Germany.

Environmental Health Perspectives
|August 1, 1990
PubMed

Insights

The fos and c-jun proteins form a complex that binds DNA. This study shows bacterial fos protein can bind DNA with c-jun, indicating post-translational modification isn't essential for complex formation.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Genetics

Background:

  • Proto-oncogenes c-fos and c-jun are crucial for the transcription factor AP1.
  • Understanding the fos protein's role in AP1 complex formation and DNA binding is essential.

Purpose of the Study:

  • To investigate the role of the fos protein in binding to the AP1 DNA recognition sequence.
  • To elucidate the mechanism of fos/c-jun complex interaction with DNA.

Main Methods:

  • Expression of a functional fos protein (Baf) in E. coli using a lambda PL promoter.
  • Biochemical purification of Baf protein.
  • In vitro complex formation with c-jun.
  • Gel retardation assays to assess DNA binding affinity.

Main Results:

  • The purified Baf protein specifically complexes with c-jun.
  • The Baf/jun complex exhibits high-affinity binding to the AP1 DNA recognition sequence.
  • Neither individual Baf nor c-jun proteins showed significant DNA binding, demonstrating cooperative binding.
  • Bacterial Baf protein, lacking glycosylation, formed a stable complex with c-jun and DNA.

Conclusions:

  • Post-translational modification of eukaryotic c-fos, specifically glycosylation, is not required for stable fos/jun/DNA complex formation.
  • Cooperative DNA binding between fos and c-jun is critical for high-affinity interaction with the AP1 site.

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