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Enhancing Binding Affinity of an Intrinsically Disordered Protein by α-Methylation of Key Amino Acid Residues

preprint
submitted on 31.10.2019 and posted on 06.11.2019 by Valentin Bauer, Boris Schmidtgall, Gergő Gógl, Jozica Dolenc, Judit Osz, Yves Nominé, Camille Kostmann, Alexandra Cousido-Siah, André Mitschler, Natacha Rochel, Gilles Travé, Bruno Kieffer, Vladimir Torbeev
Intrinsically disordered proteins (IDPs), which undergo folding upon binding to their targets, are critical players in protein interaction networks. Here we demonstrate that incorporation of non-canonical alpha-methylated amino acids into the unstructured activation domain of the transcriptional coactivator ACTR can stabilize helical conformations and strengthen binding interactions with the nuclear coactivator binding domain (NCBD) of CREB-binding protein (CBP). A combinatorial alpha-methylation scan of the ACTR sequence converged on two substitutions at positions 1055 and 1076 that increase affinity for both NCBD and the full length 270 kDa CBP by one order of magnitude. The first X-ray structure of the modified ACTR domain bound to NCBD revealed that the key alpha-methylated amino acids were localized within alpha-helices. Biophysical studies showed that the observed changes in binding energy are the result of long-range interactions and redistribution of enthalpy and entropy. This proof-of-concept study establishes a potential strategy for selective inhibition of protein-protein interactions involving IDPs in cells.

Funding

ERC Starting Grant 715062

History

Email Address of Submitting Author

torbeev@unistra.fr

Institution

University of Strasbourg

Country

FRANCE

ORCID For Submitting Author

0000-0002-7865-1044

Declaration of Conflict of Interest

No conflict of interest

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