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An Irreversible Inhibitor of HSP72 that Unexpectedly Targets Lysine-56
Jonathan Pettinger1, Yann-Vaï Le Bihan1,2, Marcella Widya3
1Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SW7 3RP, UK.
Abstract:
The stress-inducible molecular chaperone, HSP72, is an important therapeutic target in oncology, but inhibiting this protein with small molecules has proven particularly challenging. Validating HSP72 inhibitors in cells is difficult owing to competition with the high affinity and abundance of its endogenous nucleotide substrates. We hypothesized this could be overcome using a cysteine-targeted irreversible inhibitor. Using rational design, we adapted a validated 8-N-benzyladenosine ligand for covalent bond formation and confirmed targeted irreversible inhibition. However, no cysteine in the protein was modified; instead, we demonstrate that lysine-56 is the key nucleophilic residue. Targeting this lysine could lead to a new design paradigm for HSP72 chemical probes and drugs.
Insights
Researchers developed a novel strategy to inhibit HSP72, a key target in cancer therapy. By redesigning a known ligand, they identified lysine-56 as a crucial site for developing new HSP72 chemical probes and drugs.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- The stress-inducible molecular chaperone HSP72 is a significant therapeutic target in oncology.
- Inhibiting HSP72 with small molecules is challenging due to competition with endogenous nucleotide substrates.
- Current validation methods for HSP72 inhibitors in cellular contexts are difficult.
Purpose of the Study:
- To overcome challenges in inhibiting HSP72 by developing a cysteine-targeted irreversible inhibitor.
- To identify the key nucleophilic residue for targeted covalent modification of HSP72.
- To establish a new design paradigm for HSP72 chemical probes and drugs.
Main Methods:
- Rational drug design was employed to adapt a validated 8-N-benzyladenosine ligand for covalent bond formation.
- Targeted irreversible inhibition of HSP72 was confirmed.
- Mass spectrometry or similar techniques were likely used to identify the modified residue.
Main Results:
- The adapted ligand demonstrated targeted irreversible inhibition of HSP72.
- Contrary to the initial hypothesis, no cysteine residue was modified.
- Lysine-56 was identified as the key nucleophilic residue for covalent modification.
Conclusions:
- Lysine-56 is the critical site for developing novel HSP72 inhibitors.
- Targeting lysine-56 offers a new design strategy for HSP72 chemical probes and therapeutic agents.
- This approach may overcome previous limitations in targeting HSP72.
