Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex

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 aff...

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Main Authors: Crabtree, MD, Borcherds, W, Poosapati, A, Shammas, SL, Daughdrill, GW, Clarke, J
Format: Journal article
Language:English
Published: American Chemical Society 2017
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author Crabtree, MD
Borcherds, W
Poosapati, A
Shammas, SL
Daughdrill, GW
Clarke, J
author_facet Crabtree, MD
Borcherds, W
Poosapati, A
Shammas, SL
Daughdrill, GW
Clarke, J
author_sort Crabtree, MD
collection OXFORD
description 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.
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spelling oxford-uuid:5cc4c188-d3a8-41dd-927b-73573284dcd22022-03-26T17:30:13ZConserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complexJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:5cc4c188-d3a8-41dd-927b-73573284dcd2EnglishSymplectic Elements at OxfordAmerican Chemical Society2017Crabtree, MDBorcherds, WPoosapati, AShammas, SLDaughdrill, GWClarke, JAppropriate 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.
spellingShingle Crabtree, MD
Borcherds, W
Poosapati, A
Shammas, SL
Daughdrill, GW
Clarke, J
Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex
title Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex
title_full Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex
title_fullStr Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex
title_full_unstemmed Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex
title_short Conserved helix-flanking prolines modulate intrinsically disordered protein: target affinity by altering the lifetime of the bound complex
title_sort conserved helix flanking prolines modulate intrinsically disordered protein target affinity by altering the lifetime of the bound complex
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AT borcherdsw conservedhelixflankingprolinesmodulateintrinsicallydisorderedproteintargetaffinitybyalteringthelifetimeoftheboundcomplex
AT poosapatia conservedhelixflankingprolinesmodulateintrinsicallydisorderedproteintargetaffinitybyalteringthelifetimeoftheboundcomplex
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AT daughdrillgw conservedhelixflankingprolinesmodulateintrinsicallydisorderedproteintargetaffinitybyalteringthelifetimeoftheboundcomplex
AT clarkej conservedhelixflankingprolinesmodulateintrinsicallydisorderedproteintargetaffinitybyalteringthelifetimeoftheboundcomplex