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Sottini A, Borgia A, Borgia MB, Bugge K, Nettels D, Chowdhury A, Heidarsson PO, Zosel F, Best RB, Kragelund BB, Schuler B. Polyelectrolyte interactions enable rapid association and dissociation in high-affinity disordered protein complexes. Nat Commun 2020; 11:5736. [PMID: 33184256 PMCID: PMC7661507 DOI: 10.1038/s41467-020-18859-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/14/2020] [Indexed: 02/07/2023] Open
Abstract
Highly charged intrinsically disordered proteins can form complexes with very high affinity in which both binding partners fully retain their disorder and dynamics, exemplified by the positively charged linker histone H1.0 and its chaperone, the negatively charged prothymosin α. Their interaction exhibits another surprising feature: The association/dissociation kinetics switch from slow two-state-like exchange at low protein concentrations to fast exchange at higher, physiologically relevant concentrations. Here we show that this change in mechanism can be explained by the formation of transient ternary complexes favored at high protein concentrations that accelerate the exchange between bound and unbound populations by orders of magnitude. Molecular simulations show how the extreme disorder in such polyelectrolyte complexes facilitates (i) diffusion-limited binding, (ii) transient ternary complex formation, and (iii) fast exchange of monomers by competitive substitution, which together enable rapid kinetics. Biological polyelectrolytes thus have the potential to keep regulatory networks highly responsive even for interactions with extremely high affinities.
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Affiliation(s)
- Andrea Sottini
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Alessandro Borgia
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Madeleine B Borgia
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Katrine Bugge
- Structural Biology and NMR Laboratory (SBiNLab) and REPIN, Department of Biology, Ole Maaloes Vej 5, University of Copenhagen, 2200, Copenhagen, Denmark
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Aritra Chowdhury
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Pétur O Heidarsson
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
- Department of Biochemistry, Science Institute, University of Iceland, Dunhagi 3, 107, Reykjavík, Iceland
| | - Franziska Zosel
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
- Novo Nordisk A/S, Novo Nordisk Park, 2760, Måløv, Denmark
| | - Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory (SBiNLab) and REPIN, Department of Biology, Ole Maaloes Vej 5, University of Copenhagen, 2200, Copenhagen, Denmark.
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
- Department of Physics, University of Zurich, Zurich, Switzerland.
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