title: c-Abl Tyrosine Kinase Adopts Multiple Active Conformational States in Solution.
abstract: Protein tyrosine kinases of the Abl family have diverse roles in normal cellular regulation and drive several forms of leukemia as oncogenic fusion proteins. In the crystal structure of the inactive c-Abl kinase core, the SH2 and SH3 domains dock onto the back of the kinase domain, resulting in a compact, assembled state. This inactive conformation is stabilized by the interaction of the myristoylated N-cap with a pocket in the C-lobe of the kinase domain. Mutations that perturb these intramolecular interactions result in kinase activation. Here, we present X-ray scattering solution structures of multidomain c-Abl kinase core proteins modeling diverse active states. Surprisingly, the relative positions of the regulatory N-cap, SH3, and SH2 domains in an active myristic acid binding pocket mutant (A356N) were virtually identical to those of the assembled wild-type kinase core, indicating that Abl kinase activation does not require dramatic reorganization of the downregulated core structure. In contrast, the positions of the SH2 and SH3 domains in a clinically relevant imatinib-resistant gatekeeper mutant (T315I) appear to be reconfigured relative to their positions in the wild-type protein. Our results demonstrate that c-Abl kinase activation can occur either with (T315I) or without (A356N) global allosteric changes in the core, revealing the potential for previously unrecognized signaling diversity.
authors.affiliation: DeltaG Technologies , San Diego, California 92122, United States.
authors.forename: John
authors.initials: J
authors.lastname: Badger
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15219, United States.
authors.forename: Prerna
authors.initials: P
authors.lastname: Grover
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15219, United States.
authors.forename: Haibin
authors.initials: H
authors.lastname: Shi
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15219, United States.
authors.forename: Shoghag B
authors.initials: SB
authors.lastname: Panjarian
authors.forename: John R
authors.initials: JR
authors.lastname: Engen
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15219, United States.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Smithgall
authors.forename: Lee
authors.initials: L
authors.lastname: Makowski
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D019814:Myristic Acid / Q000378:metabolism*; D011487:Protein Conformation; D016315:Proto-Oncogene Proteins c-abl / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D012996:Solutions; D020349:Surface Plasmon Resonance; D018909:src Homology Domains
chemical_list: D012996:Solutions; D019814:Myristic Acid; D016315:Proto-Oncogene Proteins c-abl