Autoinhibition of Bcr-Abl through its SH3 domain.
Bcr-Abl is a dysregulated tyrosine kinase whose mechanism of activation is unclear. Here, we demonstrate that, like c-Abl, Bcr-Abl is negatively regulated through its SH3 domain. Kinase activity, transformation, and leukemogenesis by Bcr-Abl are greatly impaired by mutations of the Bcr coiled-coil domain that disrupt oligomerization, but restored by an SH3 point mutation that blocks ligand binding or a complementary mutation at the intramolecular SH3 binding site defined in c-Abl. Phosphorylation of tyrosines in the activation loop of the catalytic domain and the linker between the SH2 and catalytic domains (SH2-CD linker) is dependent on oligomerization and required for leukemogenesis. These results suggest that Bcr-Abl has a monomeric, unphosphorylated state with the SH3 domain engaged intramolecularly to Pro1124 in the SH2-CD linker, the form that is sensitive to the inhibitor imatinib (STI-571). The sole function of the coiled-coil domain is to disrupt the autoinhibited conformation through oligomerization and intermolecular autophosphorylation.
Smith
Kristen M
KM
The Center for Blood Research and Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
Yacobi
Rinat
R
Van Etten
Richard A
RA
D016475:3T3 Cells; D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D020134:Catalytic Domain / Q000187:drug effects / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005057:Eukaryotic Cells / Q000201:enzymology*; D025461:Feedback, Physiological / Q000187:drug effects / Q000235:genetics*; D016044:Fusion Proteins, bcr-abl; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology* / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D011392:Proline / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
D004791:Enzyme Inhibitors; D014443:Tyrosine; D011392:Proline; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; D000409:Alanine