TitleStrutural [sic] and dynamic NMR studies of the Crk proto-oncogene
NameSarkar, Paramita (author), Baum, Jean (chair), Kalodimos, Charalampos G (co-chair), Case, David A (internal member), Birge, Raymond B (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectChemistry and Chemical Biology,
DescriptionThe Crk family of adaptor proteins is ubiquitously expressed in most tissues and mediates the timely formation of protein complexes elicited by a variety of extracellular stimuli, including various growth and differentiation factors. This class of proteins lacks an apparent catalytic domain and may serve as adaptors, coupling different proteins of a signal transduction cascade. Crk adaptor proteins are made up of one modular Src homology 2 (SH2) and two Src homology 3 (SH3) domains. SH2 domains bind to phosphotyrosine (pTyr) containing sequence, while SH3 domain binds to proline rich motifs. The two SH3 domains are separated by long linker containing highly conserved proline reisdues. Although the role of SH2 and N-terminal SH3 (SH3N) domains of Crk has been generally delineated, the role of C-terminal SH3 (SH3C) domain remains entirely unknown. There is, however, increasing evidence that the SH3C domain along with the linker act as a regulatory element. Despite the fact that Crk has provided a model system for understanding how adaptor proteins mediate signal transduction, currently the mechanistic basis for the regulation of its function remain elusive. Such an understanding is now rendered evev more urgent because of Crk has been found to be overexpressed in many human cancers. Here, using an integrated NMR, thermodynamic, and biochemical approach, we show the presence of a unique regulatory mechanism in Crk. We have shown hat the SH3C domain serves to regulate the binding activity of the SH3N domain through an intramolecular interaction that is controlled by a prolyl cis/trans isomerization. Proline isomeerization toggles rk between two conformations: an autoinhibitory one, stabilized by the intramolecuar association of the two SH3 domains in the cis form, and an unhibited, activated one prompted by the trans form. The data provides atomic insight into the mechanisms that underpin the functionality of this binary switch and elucidate its remarkable efficiency. The results also demonstrate the interactions are mediated by novel SH3 binding surface. Also, the phosphorylation of the regulatory Tyrosine (Y222) by c-Abl is regulated by another set of prolyl-peptidyl bond, which also serve as a substrate for Cyclophilin A (CypA).
NoteIncludes bibliographical references
Noteby Paramita Sarkar
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.