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Tyr130 phosphorylation triggers Syk release from antigen receptor by long-distance conformational uncoupling.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2008 Aug 19; Vol. 105 (33), pp. 11760-5. Date of Electronic Publication: 2008 Aug 08. - Publication Year :
- 2008
-
Abstract
- The Syk protein-tyrosine kinase plays a major role in signaling through the B cell receptor for antigen (BCR). Syk binds the receptor via its tandem pair of SH2 domains interacting with a doubly phosphorylated immunoreceptor tyrosine-based activation motif (dp-ITAM) of the BCR complex. Upon phosphorylation of Tyr-130, which lies between the two SH2 domains distant to the phosphotyrosine binding sites, Syk dissociates from the receptor. To understand the structural basis for this dissociation, we investigated the structural and dynamic characteristics of the wild type tandem SH2 region (tSH2) and a variant tandem SH2 region (tSH2(pm)) with Tyr-130 substituted by Glu to permanently introduce a negative charge at this position. NMR heteronuclear relaxation experiments, residual dipolar coupling measurements and analytical ultracentrifugation revealed substantial differences in the hydrodynamic behavior of tSH2 and tSH2(pm). Although the two SH2 domains in tSH2 are tightly associated, the two domains in tSH2(pm) are partly uncoupled and tumble in solution with a faster correlation time. In addition, the equilibrium dissociation constant for the binding of tSH2(pm) to dp-ITAM (1.8 microM) is significantly higher than that for the interaction between dp-ITAM and tSH2 but is close to that for a singly tyrosine-phosphorylated peptide binding to a single SH2 domain. Experimental data and hydrodynamic calculations both suggest a loss of domain-domain contacts and change in relative orientation upon the introduction of a negative charge on residue 130. A long-distance structural mechanism by which the phosphorylation of Y130 negatively regulates the interaction of Syk with immune receptors is proposed.
- Subjects :
- Amino Acid Motifs
Animals
Crystallography, X-Ray
Mice
Models, Molecular
Nuclear Magnetic Resonance, Biomolecular
Protein Binding
Protein Structure, Quaternary
Receptors, Antigen, B-Cell chemistry
Syk Kinase
Intracellular Signaling Peptides and Proteins metabolism
Phosphotyrosine metabolism
Protein-Tyrosine Kinases metabolism
Receptors, Antigen, B-Cell metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1091-6490
- Volume :
- 105
- Issue :
- 33
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 18689684
- Full Text :
- https://doi.org/10.1073/pnas.0708583105