A sulfotyrosine motif in the human TrkB extracellular domain is required for activation by the agonist antibody ZEB85
8 affiliations
- 1Signalling and Structural Biology Lab, The Francis Crick Institute, London NW1 1AT, United Kingdom
- 2Centre of Membrane Proteins and Receptors, School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, United Kingdom
- 3School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, United Kingdom
- 4Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, United Kingdom
- 5Chemical Biology Science Technology Platform, The Francis Crick Institute, London NW1 1AT, United Kingdom
- 6Zebra Biologics Inc, Concord, MA 01742
- 7Blizard Institute, The Faculty of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, United Kingdom
- 8Institute of Structural and Molecular Biology, School of Natural Sciences, Birkbeck College, London WC1E 7HX, United Kingdom
Abstract
The brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling axis is a key effector of synaptic plasticity and neuroprotection. While TrkB activation is a major target to prevent neural dysfunction, stimulation with exogenous BDNF administration has not proven tractable given the unfavorable physiochemical properties of BDNF. In addition, BDNF also activates a cell death pathway by binding to the neurotrophin receptor p75. The TrkB agonist antibody ZEB85 provides an alternative route to the selective activation of TrkB. To understand the ZEB85 mechanism of action, we mapped the binding site for ZEB85 to the TrkB extracellular juxtamembrane domain and found a sulfotyrosine modification at residue 400 crucial for ZEB85 interaction and activation of TrkB signaling. We determined the structures of ZEB85 and BDNF bound to their respective binding sites on human TrkB suggesting independent sites for each ligand, despite prior evidence of direct competition. Using structure-guided BDNF- and ZEB85-binding deficient TrkB mutants, we assessed their ability to sequester ligands from full-length TrkB in cultured human neurons. We found that the BDNF binding site extends into the juxtamembrane domain of TrkB but does not require the sulfotyrosine 400 to activate TrkB. Together with biophysical analysis and AlphaFold modeling, these results explain how BDNF can displace ZEB85 from TrkB through an overlapping epitope. Our findings reveal unique features of TrkB, not present in the related neurotrophin receptors TrkA and TrkC and suggest future directions to explore the role of sulfotyrosine in TrkB signaling.
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BibTeX
@article{briggs2026sulfotyrosine,
title = {{A sulfotyrosine motif in the human TrkB extracellular domain is required for activation by the agonist antibody ZEB85}},
author = {David C. Briggs and Ryan T. Duffy and Sarah Ateaque and Sarah Maslen and Hema Nagaraj and Yves-Alain Barde and Peter S. DiStefano and Ronald M. Lindsay and Paul C. Armstrong and Chloe J. Peach and Neil Q. McDonald},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2618780123},
url = {https://doi.org/10.1073/pnas.2618780123},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A sulfotyrosine motif in the human TrkB extracellular domain is required for activation by the agonist antibody ZEB85
AU - David C. Briggs
AU - Ryan T. Duffy
AU - Sarah Ateaque
AU - Sarah Maslen
AU - Hema Nagaraj
AU - Yves-Alain Barde
AU - Peter S. DiStefano
AU - Ronald M. Lindsay
AU - Paul C. Armstrong
AU - Chloe J. Peach
AU - Neil Q. McDonald
PY - 2026
DA - 2026/10/29
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2618780123
UR - https://doi.org/10.1073/pnas.2618780123
AB - The brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling axis is a key effector of synaptic plasticity and neuroprotection. While TrkB activation is a major target to prevent neural dysfunction, stimulation with exogenous BDNF administration has not proven tractable given the unfavorable physiochemical properties of BDNF. In addition, BDNF also activates a cell death pathway by binding to the neurotrophin receptor p75. The TrkB agonist antibody ZEB85 provides an alternative route to the selective activation of TrkB. To understand the ZEB85 mechanism of action, we mapped the binding site for ZEB85 to the TrkB extracellular juxtamembrane domain and found a sulfotyrosine modification at residue 400 crucial for ZEB85 interaction and activation of TrkB signaling. We determined the structures of ZEB85 and BDNF bound to their respective binding sites on human TrkB suggesting independent sites for each ligand, despite prior evidence of direct competition. Using structure-guided BDNF- and ZEB85-binding deficient TrkB mutants, we assessed their ability to sequester ligands from full-length TrkB in cultured human neurons. We found that the BDNF binding site extends into the juxtamembrane domain of TrkB but does not require the sulfotyrosine 400 to activate TrkB. Together with biophysical analysis and AlphaFold modeling, these results explain how BDNF can displace ZEB85 from TrkB through an overlapping epitope. Our findings reveal unique features of TrkB, not present in the related neurotrophin receptors TrkA and TrkC and suggest future directions to explore the role of sulfotyrosine in TrkB signaling.
SN - 0027-8424
SN - 1091-6490
ER -