spacer The NMR ensemble structure of the Itk SH2 domain bound to a phosphopeptide
Primary citation
Title Molecular Details of Itk Activation by Prolyl Isomerization and Phospholigand Binding: The NMR Structure of the Itk SH2 Domain Bound to a Phosphopeptide.
Authors Pletneva, E.V.search; Sundd, M.search; Fulton, D.B.search; Andreotti, A.H.search
Journal J.MOL.BIOL.search vol:357, pag:550-561 (2006), Identifiers: PubMed ID (16436281)search DOI (10.1016/j.jmb.2005.12.073)
Abstract The Src homology 2 (SH2) domain of interleukin-2 tyrosine kinase (Itk) is a critical component of the regulatory apparatus controlling the activity of this immunologically important enzyme. To gain insight into the structural features associated with the activated form of Itk, we have solved the NMR structure of the SH2 domain bound to a phosphotyrosine-containing peptide (pY) and analyzed changes in trans-hydrogen bond scalar couplings ((3h)J(NC')) that result from pY binding. Isomerization of a single prolyl imide bond in this domain is responsible for simultaneous existence of two distinct SH2 conformers. Prolyl isomerization directs ligand recognition: the trans conformer preferentially binds pY. The structure of the SH2/pY complex provides insight into the ligand specificity; the BG loop in the ligand-free trans SH2 conformer is pre-arranged for optimal contacts with the pY+3 residue of the ligand. Analysis of (3h)J(NC') couplings arising from hydrogen bonds has revealed propagation of structural changes from the pY binding pocket to the CD loop containing conformationally heterogeneous proline as well as to the alphaB helix, on the opposite site of the domain. These findings offer a structural framework for understanding the roles of prolyl isomerization and pY binding in Itk regulation.
MeSH terms Amino Acid Sequencesearch, Enzyme Activationsearch, Hydrogen Bondingsearch, Isomerismsearch, Ligandssearch, Modelssearch, Molecularsearch, Molecular Sequence Datasearch, Nuclear Magnetic Resonancesearch, Biomolecularsearch, Phosphopeptidessearch, Prolinesearch, Protein Bindingsearch, Protein Structuresearch, Tertiarysearch, Protein-Tyrosine Kinasessearch, src Homology Domainssearch
Other entries described in this publication 2etz
Secondary citations
Title Structural characterization of a proline-driven conformational switch within the Itk SH2 domain
Authors Mallis, R.J.search; Brazin, K.N.search; Fulton, D.B.search; Andreotti, A.H.search
Journal NAT.STRUCT.BIOL.search vol:9, pag:900-905 (2002), Identifiers: PubMed ID (12402030)search DOI (10.1038/nsb864)
Abstract Interleukin-2 tyrosine kinase (Itk) is a T cell-specific kinase required for a proper immune response following T cell receptor engagement. In addition to the kinase domain, Itk is composed of several noncatalytic regulatory domains, including a Src homology 2 (SH2) domain that contains a conformationally heterogeneous Pro residue. Cis-trans isomerization of a single prolyl imide bond within the SH2 domain mediates conformer-specific ligand recognition that may have functional implications in T cell signaling. To better understand the mechanism by which a proline switch regulates ligand binding, we have used NMR spectroscopy to determine two structures of Itk SH2 corresponding to the cis and trans imide bond-containing conformers. The structures indicate that the heterogeneous Pro residue acts as a hinge that modulates ligand recognition by controlling the relative orientation of protein-binding surfaces.
MeSH terms Amino Acid Sequencesearch, Animalssearch, Hydrophobic and Hydrophilic Interactionssearch, Imidessearch, Isomerismsearch, Ligandssearch, Modelssearch, Molecularsearch, Molecular Sequence Datasearch, Nuclear Magnetic Resonancesearch, Biomolecularsearch, Prolinesearch, Protein Conformationsearch, Protein-Tyrosine Kinasessearch, Sequence Alignmentsearch, src Homology Domainssearch
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