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Native MS and ligand observed NMR uncovers subtle SLiM binding variations that mediate HSP90-Hop PPI modulation

Tara K Davids1, Daniel A Kusza1, Shannon K Misplon1

  • 1Department of Chemistry, University of Cape Town, Rondebosch Cape Town 7701 South Africa Marwaan.rylands@uct.ac.za Clinton.veale@uct.ac.za.

RSC Chemical Biology
|May 14, 2026
PubMed

Insights

A novel tetrazole-containing peptide disrupts Heat Shock Protein 90 (HSP90) interactions by altering its binding mode, not affinity. This discovery offers a new strategy for developing protein-protein interaction (PPI) inhibitors for drug discovery.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Drug Discovery

Background:

  • Heat Shock Protein 90 (HSP90) is crucial for cellular proteostasis.
  • HSP90 interacts with co-chaperones like Hop via its C-terminal MEEVD motif.
  • Targeting HSP90-co-chaperone interactions is a promising therapeutic strategy.

Purpose of the Study:

  • Investigate why a non-natural tetrazole peptide (2) inhibits HSP90-Hop interaction more effectively than the native MEEVD motif (1).
  • Determine the structural basis for differential inhibition of protein-protein interactions (PPIs).

Main Methods:

  • Native mass spectrometry (nMS) with ion mobility (IM).
  • Saturation transfer difference (STD) NMR.
  • Water ligand observed via gradient spectroscopy (WLOGSY) NMR.
  • Analysis of peptide derivatives binding to the HopTPR2A domain.

Main Results:

  • Peptide 2, mimicking the MEEVD motif, disrupts HSP90-Hop PPIs.
  • Native MEEVD peptide (1) showed weak inhibition despite similar binding affinity.
  • Differences in PPI modulation stem from altered binding modes, not affinity, due to sequence variations.
  • Conformational stability and magnetization transfer varied subtly between peptides.

Conclusions:

  • The study provides a structural basis for designing peptidomimetic inhibitors of HSP90-Hop PPIs.
  • Altered binding modes, rather than affinity, are key to modulating transient PPIs.
  • A generalized strategy for targeting transient PPIs in drug discovery is presented.

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