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Truncated and helix-constrained peptides with high affinity and specificity for the cFos coiled-coil of AP-1.

Rao, Tara and Ruiz-Gómez, Gloria and Hill, Timothy A and Hoang, Huy N and Fairlie, David P and Mason, Jody M (2013) 'Truncated and helix-constrained peptides with high affinity and specificity for the cFos coiled-coil of AP-1.' PloS One, 8 (3). e59415. ISSN 1932-6203

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Abstract

Protein-based therapeutics feature large interacting surfaces. Protein folding endows structural stability to localised surface epitopes, imparting high affinity and target specificity upon interactions with binding partners. However, short synthetic peptides with sequences corresponding to such protein epitopes are unstructured in water and promiscuously bind to proteins with low affinity and specificity. Here we combine structural stability and target specificity of proteins, with low cost and rapid synthesis of small molecules, towards meeting the significant challenge of binding coiled coil proteins in transcriptional regulation. By iteratively truncating a Jun-based peptide from 37 to 22 residues, strategically incorporating i-->i+4 helix-inducing constraints, and positioning unnatural amino acids, we have produced short, water-stable, alpha-helical peptides that bind cFos. A three-dimensional NMR-derived structure for one peptide (24) confirmed a highly stable alpha-helix which was resistant to proteolytic degradation in serum. These short structured peptides are entropically pre-organized for binding with high affinity and specificity to cFos, a key component of the oncogenic transcriptional regulator Activator Protein-1 (AP-1). They competitively antagonized the cJun–cFos coiled-coil interaction. Truncating a Jun-based peptide from 37 to 22 residues decreased the binding enthalpy for cJun by ~9 kcal/mol, but this was compensated by increased conformational entropy (TDS ≤ 7.5 kcal/mol). This study demonstrates that rational design of short peptides constrained by alpha-helical cyclic pentapeptide modules is able to retain parental high helicity, as well as high affinity and specificity for cFos. These are important steps towards small antagonists of the cJun-cFos interaction that mediates gene transcription in cancer and inflammatory diseases.

Item Type: Article
Subjects: Q Science > Q Science (General)
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Jody Mason
Date Deposited: 15 Feb 2013 13:00
Last Modified: 16 Dec 2014 11:15
URI: http://repository.essex.ac.uk/id/eprint/5627

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