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Structural and biophysical characterization of the Syk activation switch
Ulrich Grädler1, Daniel Schwarz, Verena Dresing
1Merck KGaA, Merck Serono Research, Small Molecule Platform/MIB, Frankfurter Str. 250, 64293 Darmstadt, Germany. ulrich.graedler@merckgroup.com
Journal of Molecular Biology
|November 17, 2012
Summary
This study reveals the first crystal structures of full-length Syk (fl-Syk), showing an autoinhibited conformation. Syk inhibitor binding is modulated by pITAMs, impacting autoimmune and inflammation disease treatments.
Area of Science:
- Biochemistry
- Structural Biology
- Immunology
Background:
- Spleen tyrosine kinase (Syk) is crucial for intracellular immune signaling.
- Syk kinase activity is regulated by pITAM binding and autophosphorylation.
- Targeting Syk offers potential for treating autoimmune and inflammatory diseases.
Purpose of the Study:
- To determine the first crystal structures of full-length Syk (fl-Syk).
- To investigate the structural and thermodynamic basis of Syk inhibition.
- To explore the impact of pITAM binding on Syk conformation and activity.
Main Methods:
- X-ray crystallography of full-length Syk (wild type and mutant) with AMP-PNP.
- Surface Plasmon Resonance (SPR) for ligand binding studies.
- Isothermal Titration Calorimetry (ITC) for thermodynamic analysis of inhibitor interactions.
Main Results:
- First crystal structures of fl-Syk reveal an autoinhibited conformation.
- Conformational differences exist between autoinhibited and activated Syk ATP sites.
- pITAM binding modulates Syk inhibitor binding affinity and thermodynamic signatures.
- pITAM binding strongly stimulates Syk autophosphorylation in vitro.
Conclusions:
- Syk's autoinhibited structure provides insights into its regulation.
- pITAM interaction with the tSH2 domain influences kinase activity and inhibitor binding.
- Syk exhibits distinct conformational dynamics compared to ZAP-70, suggesting unique regulatory mechanisms.
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