Dynamic control of selectivity in the ubiquitination pathway revealed by an ASP to GLU substitution in an intra-molecular salt-bridge network

S.J.L. van Wijk, A.S.J. Melquiond, S.J. de Vries, H.T.M. Timmers, A.M.J.J. Bonvin

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Ubiquitination relies on a subtle balance between selectivity and promiscuity achieved through specific interactions between ubiquitin-conjugating enzymes (E2s) and ubiquitin ligases (E3s). Here, we report how a single aspartic to glutamic acid substitution acts as a dynamic switch to tip the selectivity balance of human E2s for interaction toward E3 RING-finger domains. By combining molecular dynamic simulations, experimental yeast-two-hybrid screen of E2-E3 (RING) interactions and mutagenesis, we reveal how the dynamics of an internal salt-bridge network at the rim of the E2-E3 interaction surface controls the balance between an "open", binding competent, and a "closed", binding incompetent state. The molecular dynamic simulations shed light on the fine mechanism of this molecular switch and allowed us to identify its components, namely an aspartate/glutamate pair, a lysine acting as the central switch and a remote aspartate. Perturbations of single residues in this network, both inside and outside the interaction surface, are sufficient to switch the global E2 interaction selectivity as demonstrated experimentally. Taken together, our results indicate a new mechanism to control E2-E3 interaction selectivity at an atomic level, highlighting how minimal changes in amino acid side-chain affecting the dynamics of intramolecular salt-bridges can be crucial for protein-protein interactions. These findings indicate that the widely accepted sequence-structure-function paradigm should be extended to sequence-structure-dynamics-function relationship and open new possibilities for control and fine-tuning of protein interaction selectivity.

Original languageEnglish
Article numbere1002754
Number of pages1
JournalPLoS Computational Biology
Volume8
Issue number11
DOIs
Publication statusPublished - 2012

Keywords

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Aspartic Acid/chemistry
  • Computational Biology
  • Glutamic Acid/chemistry
  • Humans
  • Hydrogen Bonding
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • Reproducibility of Results
  • Sequence Alignment
  • Static Electricity
  • Two-Hybrid System Techniques
  • Ubiquitin-Conjugating Enzymes/chemistry
  • Ubiquitin-Protein Ligases/chemistry
  • Ubiquitination/genetics

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