title: Binding Mechanism of the N-Terminal SH3 Domain of CrkII and Proline-Rich Motifs in cAbl.
abstract: The N-terminal Src homology 3 (nSH3) domain of a signaling adaptor protein, CT-10 regulator of kinase II (CrkII), recognizes proline-rich motifs (PRMs) of binding partners, such as cAbl kinase. The interaction between CrkII and cAbl kinase is involved in the regulation of cell spreading, microbial pathogenesis, and cancer metastasis. Here, we report the detailed biophysical characterizations of the interactions between the nSH3 domain of CrkII and PRMs in cAbl. We identified that the nSH3 domain of CrkII binds to three PRMs in cAbl with virtually identical affinities. Structural studies, by using x-ray crystallography and NMR spectroscopy, revealed that the binding modes of all three nSH3:PRM complexes are highly similar to each other. Van 't Hoff analysis revealed that nSH3:PRM interaction is associated with favorable enthalpy and unfavorable entropy change. The combination of experimentally determined thermodynamic parameters, structure-based calculations, and (15)N NMR relaxation analysis highlights the energetic contribution of conformational entropy change upon the complex formation, and water molecules structured in the binding interface of the nSH3:PRM complex. Understanding the molecular basis of nSH3:PRM interaction will provide, to our knowledge, new insights for the rational design of small molecules targeting the interaction between CrkII and cAbl.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas.
authors.forename: Veer S
authors.initials: VS
authors.lastname: Bhatt
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas.
authors.forename: Danyun
authors.initials: D
authors.lastname: Zeng
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas.
authors.forename: Inna
authors.initials: I
authors.lastname: Krieger
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas.
authors.forename: James C
authors.initials: JC
authors.lastname: Sacchettini
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas. Electronic address: jaehyuncho@tamu.edu.
authors.forename: Jae-Hyun
authors.initials: JH
authors.lastname: Cho
mesh_terms: D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D006801:Humans; D008958:Models, Molecular; D009010:Monte Carlo Method; D019906:Nuclear Magnetic Resonance, Biomolecular; D011392:Proline / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D016315:Proto-Oncogene Proteins c-abl / Q000235:genetics / Q000378:metabolism*; D050737:Proto-Oncogene Proteins c-crk / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics; D014867:Water / Q000378:metabolism; D018909:src Homology Domains / Q000235:genetics
chemical_list: D050737:Proto-Oncogene Proteins c-crk; D014867:Water; D011392:Proline; D016315:Proto-Oncogene Proteins c-abl