Conserved Helix-Flanking Prolines Modulate Intrinsically Disordered Protein:Target Affinity by Altering the Lifetime of the Bound Complex.
Shammas, Sarah L
Daughdrill, Gary W
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Crabtree, M., Borcherds, W., Poosapati, A., Shammas, S. L., Daughdrill, G. W., & Clarke, J. (2017). Conserved Helix-Flanking Prolines Modulate Intrinsically Disordered Protein:Target Affinity by Altering the Lifetime of the Bound Complex.. Biochemistry, 56 (18), 2379-2384. https://doi.org/10.1021/acs.biochem.7b00179
Appropriate integration of cellular signals requires a delicate balance of ligand-target binding affinities. Increasing the level of residual structure in intrinsically disordered proteins (IDPs), which are overrepresented in these cellular processes, has been shown previously to enhance binding affinities and alter cellular function. Conserved proline residues are commonly found flanking regions of IDPs that become helical upon interacting with a partner protein. Here, we mutate these helix-flanking prolines in p53 and MLL and find opposite effects on binding affinity upon an increase in free IDP helicity. In both cases, changes in affinity were due to alterations in dissociation, not association, rate constants, which is inconsistent with conformational selection mechanisms. We conclude that, contrary to previous suggestions, helix-flanking prolines do not regulate affinity by modulating the rate of complex formation. Instead, they influence binding affinities by controlling the lifetime of the bound complex.
Animals, Humans, Mice, Escherichia coli, Histone-Lysine N-Methyltransferase, Proline, Membrane Proteins, Phosphoproteins, Recombinant Proteins, Cloning, Molecular, Sequence Alignment, Gene Expression, Binding Sites, Amino Acid Sequence, Conserved Sequence, Protein Binding, Protein Folding, Sequence Homology, Amino Acid, Mutation, Models, Molecular, Tumor Suppressor Protein p53, Myeloid-Lymphoid Leukemia Protein, Protein Interaction Domains and Motifs, Intrinsically Disordered Proteins, Protein Conformation, alpha-Helical
Wellcome Trust (095195/Z/10/Z)
External DOI: https://doi.org/10.1021/acs.biochem.7b00179
This record's URL: https://www.repository.cam.ac.uk/handle/1810/274312