p38α MAP Kinase Dimers with Swapped Activation Segments and a Novel Catalytic Loop Conformation
| Autor: | Kenneth A. Johnson, Espen Åberg, Richard A. Engh, Tom Egil Hansen, Ulli Rothweiler, Jorunn B. Jørgensen |
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| Rok vydání: | 2011 |
| Předmět: |
Models
Molecular Dimer Molecular Sequence Data Salmo salar Protein Data Bank (RCSB PDB) Mitogen-activated protein kinase kinase Crystallography X-Ray p38 Mitogen-Activated Protein Kinases chemistry.chemical_compound Structural Biology Animals Amino Acid Sequence Phosphorylation Protein Structure Quaternary Protein kinase A Molecular Biology Sequence Homology Amino Acid biology Kinase Autophosphorylation chemistry Biochemistry Mitogen-activated protein kinase biology.protein Biophysics Tyrosine Protein Multimerization |
| Zdroj: | Journal of Molecular Biology. 411:474-485 |
| ISSN: | 0022-2836 |
| DOI: | 10.1016/j.jmb.2011.06.013 |
| Popis: | Many protein kinase functions, including autophosphorylation in trans, require dimerization, possibly by activation segment exchange. Such dimers have been reported for a few autophosphorylating protein kinases, but not for mitogen-activated protein kinases (MAPKs). Activation of MAPKs proceeds not only via the well-characterized action of dual T/Y specificity MAPK kinases, phosphorylating both residues of the MAPK TxY activation loop motif, but also via a noncanonical activation pathway triggered by phosphorylation at Tyr323 and homodimerization. Here, we report the 2. 7-A-resolution structure of p38α MAPK from Salmo salar in a novel domain-swapped homodimeric form. The tyrosines of the conserved sequence YxAPE anchor the swapped activation segments in a configuration suitable for autophosphorylation in trans and provide a model for the noncanonical pathway. In the dimer, a structural unit containing Tyr323 is formed at a dimerization contact region that stabilizes the HRD catalytic loop in a unique inactive geometry. This feature is consistent with the requirement of Tyr323 phosphorylation for the initiation of the noncanonical pathway. Despite the interacting surface of more than 2600 A2, the dimer is not obligate, as gel filtration shows the dimerization to occur only at relatively high concentrations. The transition from monomer to dimer involves a relatively simple hinged displacement of helix EF and adjacent residues. Thus, dimer formation is likely to be transient, compatible with functional requirements for autophosphorylation, allowing further modulation, for example, by scaffolding mechanisms. |
| Databáze: | OpenAIRE |
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