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fos-jun conspiracy: implications for the cell

I M Verma1, L J Ransone, J Visvader

  • 1Molecular Biology and Virology Laboratory, Salk Institute, San Diego, CA 92138.

Ciba Foundation Symposium
|January 1, 1990
PubMed

Insights

The fos and jun proteins form a stable complex (AP-1) that binds DNA. The fos protein

Area of Science:

  • Molecular Biology
  • Oncogenesis
  • Transcription Factors

Background:

  • Nuclear oncoproteins fos and jun (AP-1) form stable heterodimers.
  • The leucine zipper domain is essential for heterodimer formation.
  • The AP-1 complex binds to specific DNA sequences with high affinity.

Purpose of the Study:

  • To investigate the roles of fos and jun protein domains in DNA binding.
  • To determine the contribution of the basic region to the transcriptional complex's DNA binding affinity.
  • To explore the potential of fos and jun mutants as dominant-negative regulators.

Main Methods:

  • Site-directed mutagenesis of fos and jun proteins, focusing on the leucine zipper and basic regions.
  • Analysis of protein complex formation and DNA binding affinity.
  • Assessment of dominant-negative effects of mutant proteins on normal fos cellular function.

Main Results:

  • Mutations in the leucine zipper domain did not affect heterodimer formation.
  • The basic region of fos is critical for determining DNA binding affinity.
  • Mutations in fos basic amino acids prevented DNA binding, even with wild-type jun.
  • Mutants in the basic regions of fos and jun can function as dominant-negative inhibitors.

Conclusions:

  • Fos protein plays a dominant role in jun-fos DNA binding, despite lacking DNA binding capability alone.
  • The basic region of fos is crucial for high-affinity DNA binding of the AP-1 complex.
  • Engineered fos and jun mutants offer a strategy to inhibit normal fos function in cellular processes.

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