Differential sensitivity of Src-family kinases to activation by SH3 domain displacement

• Published in: PloS one Vol. 9; no. 8; p. e105629
• Main Authors: Moroco, Jamie A, Craigo, Jodi K, Iacob, Roxana E, Wales, Thomas E, Engen, John R, Smithgall, Thomas E
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.08.2014; Public Library of Science (PLoS)
• Subjects: Activation; Amino acids; Binding; Biochemistry; Biology; Biology and Life Sciences; Catalysis; Chemistry; Displacement; Enzyme Activation - genetics; Fyn protein; Gene expression; Humans; Kinases; Medicine; Mutation; Peptides; Peptides - chemistry; Peptides - genetics; Peptides - metabolism; Phosphorylation; Phosphotransferases; Phosphotyrosine; Proteins; Regulatory mechanisms (biology); Sensitivity; Signal Transduction; Signaling; src Homology Domains; Src protein; src-Family Kinases - chemistry; src-Family Kinases - genetics; src-Family Kinases - metabolism; Tyrosine; Pittsburgh Pennsylvania; United States > US; Massachusetts; Wales; Pennsylvania
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0105629

Src-family kinases (SFKs) are non-receptor protein-tyrosine kinases involved in a variety of signaling pathways in virtually every cell type. The SFKs share a common negative regulatory mechanism that involves intramolecular interactions of the SH3 domain with the PPII helix formed by the SH2-kinase linker as well as the SH2 domain with a conserved phosphotyrosine residue in the C-terminal tail. Growing evidence suggests that individual SFKs may exhibit distinct activation mechanisms dictated by the relative strengths of these intramolecular interactions. To elucidate the role of the SH3:linker interaction in the regulation of individual SFKs, we used a synthetic SH3 domain-binding peptide (VSL12) to probe the sensitivity of downregulated c-Src, Hck, Lyn and Fyn to SH3-based activation in a kinetic kinase assay. All four SFKs responded to VSL12 binding with enhanced kinase activity, demonstrating a conserved role for SH3:linker interaction in the control of catalytic function. However, the sensitivity and extent of SH3-based activation varied over a wide range. In addition, autophosphorylation of the activation loops of c-Src and Hck did not override regulatory control by SH3:linker displacement, demonstrating that these modes of activation are independent. Our results show that despite the similarity of their downregulated conformations, individual Src-family members show diverse responses to activation by domain displacement which may reflect their adaptation to specific signaling environments in vivo.