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FRS2 PTB domain conformation regulates interactions with divergent neurotrophic receptors
Kelley S Yan1, Miklos Kuti, Sherry Yan
1Structural Biology Program, Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York University, New York, New York 10029, USA.
Abstract:
Membrane-anchored adaptor proteins FRS2alpha/beta (also known as SNT-1/2) mediate signaling of fibroblast growth factor receptors (FGFRs) and neurotrophin receptors (TRKs) through their N-terminal phosphotyrosine binding (PTB) domains. The FRS2 PTB domain recognizes tyrosine-phosphorylated TRKs at an NPXpY (where pY is phosphotyrosine) motif, whereas its constitutive association with FGFR involves a receptor juxtamembrane region lacking Tyr and Asn residues. Here we show by isothermal titration calorimetry that the FRS2alpha PTB domain binding to peptides derived from TRKs or FGFR is thermodynamically different. TRK binding is largely enthalpy-driven, whereas the FGFR interaction is governed by a favorable entropic contribution to the free energy of binding. Furthermore, our NMR spectral analysis suggests that disruption of an unstructured region C-terminal to the PTB domain alters local conformation and dynamics of the residues at the ligand-binding site, and that structural disruption of the beta8-strand directly weakens the PTB domain association with the FGFR ligand. Together, our new findings support a molecular mechanism by which conformational dynamics of the FRS2alpha PTB domain dictates its association with either fibroblast growth factor or neurotrophin receptors in neuronal development.
Insights
Membrane adaptor proteins FRS2alpha/beta (SNT-1/2) link fibroblast growth factor receptors (FGFRs) and neurotrophin receptors (TRKs) to cellular signaling. Their binding mechanisms differ, with TRK interaction being enthalpy-driven and FGFR interaction being entropy-driven, impacting neuronal development.
Area of Science:
- Molecular biology
- Cell signaling
- Neuroscience
Background:
- Membrane-anchored adaptor proteins FRS2alpha/beta (SNT-1/2) are crucial for signaling pathways involving fibroblast growth factor receptors (FGFRs) and neurotrophin receptors (TRKs).
- The phosphotyrosine binding (PTB) domain of FRS2 mediates these interactions, recognizing specific motifs on TRKs and juxtamembrane regions of FGFRs.
Purpose of the Study:
- To investigate the thermodynamic and structural differences in the binding of the FRS2alpha PTB domain to TRK and FGFR ligands.
- To elucidate the molecular mechanism underlying FRS2alpha's differential receptor association in neuronal development.
Main Methods:
- Isothermal titration calorimetry (ITC) was used to determine the binding thermodynamics.
- Nuclear magnetic resonance (NMR) spectroscopy was employed to analyze structural and dynamic changes in the FRS2alpha PTB domain.
Main Results:
- The FRS2alpha PTB domain exhibits distinct binding thermodynamics for TRK (enthalpy-driven) and FGFR (entropy-driven) peptides.
- NMR analysis revealed that conformational dynamics of the PTB domain, particularly alterations in the C-terminal unstructured region and beta8-strand, influence ligand binding affinity.
Conclusions:
- Conformational dynamics of the FRS2alpha PTB domain play a critical role in dictating its specific association with either FGFRs or TRKs.
- This differential binding mechanism provides insight into the regulation of signaling pathways essential for neuronal development.