Downsizing proto-oncogene cFos to short helix-constrained peptides that bind Jun

Daniel Baxter, Samuel Perry, Timothy Hill, Woan Kok, Nathan Zaccai, Leo Brady, David Fairlie, Jody Mason

Research output: Contribution to journalArticle

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Abstract

The oncogenic transcription factor Activator Protein-1 (AP-1) is a DNA binding protein that assembles through dimerization of Fos and Jun protein subunits, their leucine-rich helical sequences entwining into a coiled coil structure. This study reports on downsizing the protooncogene cFos protein (380 residues) to shorter peptides (37-25 residues), modified with helix-inducing constraints to enhance binding to Jun. A crystal structure is reported for a 37-residue Fos-derived peptide (FosW) bound to Jun. This guided iterative downsizing of FosW to shorter peptide sequences, constrained into stable water-soluble alpha helices by connecting amino acid sidechains to form cyclic pentapeptide components. Structural integrity in the presence and absence of Jun was assessed by circular dichroism spectroscopy, while thermodynamics of binding to cFos was measured by isothermal titration calorimetry. A 25-residue constrained peptide, one-third shorter yet 25 % more helical than the structurally characterised 37-residue Fos-derived peptide, retained 80 % of the binding free energy due to pre-organisation in a Jun-binding helix conformation, with entropy gain (TΔS = + 3.2 kcal/mol) compensating for enthalpy loss. Attaching a cell penetrating peptide (TAT48-57) and a nuclear localisation signal (SV40) promoted cell uptake, localisation to the nucleus, and inhibition of the proliferation of
two breast cancer cell lines.
Original languageEnglish
Pages (from-to)2051-2061
JournalACS Chemical Biology
Volume12
Issue number8
DOIs
Publication statusPublished - 17 Aug 2017

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Proto-Oncogenes
Peptides
Cell-Penetrating Peptides
Circular dichroism spectroscopy
Nuclear Localization Signals
Calorimetry
Dimerization
Transcription Factor AP-1
Protein Subunits
DNA-Binding Proteins
Entropy
Structural integrity
Circular Dichroism
Titration
Thermodynamics
Leucine
Free energy
Conformations
Enthalpy
Spectrum Analysis

Keywords

  • coiled coils
  • activator protein-1
  • helix-constrained peptides
  • Transcription factor

Cite this

Downsizing proto-oncogene cFos to short helix-constrained peptides that bind Jun. / Baxter, Daniel; Perry, Samuel; Hill, Timothy; Kok, Woan; Zaccai, Nathan; Brady, Leo; Fairlie, David; Mason, Jody.

In: ACS Chemical Biology, Vol. 12, No. 8, 17.08.2017, p. 2051-2061.

Research output: Contribution to journalArticle

Baxter, D, Perry, S, Hill, T, Kok, W, Zaccai, N, Brady, L, Fairlie, D & Mason, J 2017, 'Downsizing proto-oncogene cFos to short helix-constrained peptides that bind Jun', ACS Chemical Biology, vol. 12, no. 8, pp. 2051-2061. https://doi.org/10.1021/acschembio.7b00303
Baxter, Daniel ; Perry, Samuel ; Hill, Timothy ; Kok, Woan ; Zaccai, Nathan ; Brady, Leo ; Fairlie, David ; Mason, Jody. / Downsizing proto-oncogene cFos to short helix-constrained peptides that bind Jun. In: ACS Chemical Biology. 2017 ; Vol. 12, No. 8. pp. 2051-2061.
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