Tryptoline stereoprobe elaboration identifies inhibitors of the GRPEL1–HSPA9 complex
6 affiliations
- 1Department of Chemistry, Scripps Research, La Jolla, CA, USA
- 2Department of Chemistry, University of Oxford, Oxford, UK
- 3Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
- 4Department of Biochemistry and Molecular Biophysics, University of California, San Diego, La Jolla, CA, USA
- 5Department of Chemistry, Scripps Research, La Jolla, CA, USA. [email protected]
- 6Department of Chemistry, Scripps Research, La Jolla, CA, USA. [email protected]
Abstract
Activity-based protein profiling has identified hundreds of human proteins from diverse classes that react at cysteine residues with stereochemically defined electrophilic compounds (stereoprobes). The structure-activity relationships underlying these stereoprobe-protein interactions, however, remain poorly understood. Here, we show that the protein interaction landscape of tryptoline acrylamide stereoprobes can be profoundly altered by structural modifications distal to the acrylamide reactive group. Most stereoprobe liganding events occurred at nonorthosteric sites and evaded assignment by the machine learning-based cofolding model Boltz-2, which instead tended to misplace stereoprobes in orthosteric pockets (an outcome we term 'orthostery burnout'). We found that stereoprobes reacting with C124 in the nucleotide exchange factor GRPEL1 disrupt interactions with the mitochondrial HSP70 chaperone HSPA9/mortalin, leading to impairments in mitochondrial protein import and mitophagy induction. Our results highlight tryptoline acrylamides as a versatile source of covalent ligands targeting nonorthosteric sites on proteins, including tool compounds that perturb the mitochondrial HSP70 chaperone system.
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BibTeX
@article{hayward2026tryptoline,
title = {{Tryptoline stereoprobe elaboration identifies inhibitors of the GRPEL1–HSPA9 complex}},
author = {Rachel E. Hayward and Raymond F. Berkeley and Zijian Gao and Maximilian Garhammer and Marc A. Morizono and Evert Njomen and Haoxin Li and Kristen E. DeMeester and Victor Cociorva and Mark A. Herzik and F. Ulrich Hartl and Bruno N. Melillo and Benjamin F. Cravatt},
journal = {Nature Chemical Biology},
year = {2026},
month = oct,
doi = {10.1038/s41589-026-02348-1},
url = {https://doi.org/10.1038/s41589-026-02348-1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Tryptoline stereoprobe elaboration identifies inhibitors of the GRPEL1–HSPA9 complex
AU - Rachel E. Hayward
AU - Raymond F. Berkeley
AU - Zijian Gao
AU - Maximilian Garhammer
AU - Marc A. Morizono
AU - Evert Njomen
AU - Haoxin Li
AU - Kristen E. DeMeester
AU - Victor Cociorva
AU - Mark A. Herzik
AU - F. Ulrich Hartl
AU - Bruno N. Melillo
AU - Benjamin F. Cravatt
PY - 2026
DA - 2026/10/16
JO - Nature Chemical Biology
DO - 10.1038/s41589-026-02348-1
UR - https://doi.org/10.1038/s41589-026-02348-1
AB - Activity-based protein profiling has identified hundreds of human proteins from diverse classes that react at cysteine residues with stereochemically defined electrophilic compounds (stereoprobes). The structure-activity relationships underlying these stereoprobe-protein interactions, however, remain poorly understood. Here, we show that the protein interaction landscape of tryptoline acrylamide stereoprobes can be profoundly altered by structural modifications distal to the acrylamide reactive group. Most stereoprobe liganding events occurred at nonorthosteric sites and evaded assignment by the machine learning-based cofolding model Boltz-2, which instead tended to misplace stereoprobes in orthosteric pockets (an outcome we term 'orthostery burnout'). We found that stereoprobes reacting with C124 in the nucleotide exchange factor GRPEL1 disrupt interactions with the mitochondrial HSP70 chaperone HSPA9/mortalin, leading to impairments in mitochondrial protein import and mitophagy induction. Our results highlight tryptoline acrylamides as a versatile source of covalent ligands targeting nonorthosteric sites on proteins, including tool compounds that perturb the mitochondrial HSP70 chaperone system.
SN - 1552-4450
SN - 1552-4469
ER -