The interaction of the Bcr-Abl tyrosine kinase with the Src kinase Hck is mediated by multiple binding domains.
Bcr-Abl is found in more than 95% of cases with CML. The mechanism of Bcr-Abl-induced transformation is not fully understood. Bcr-Abl is a constitutively active tyrosine kinase with transforming capacity for hematopoietic cells. We demonstrated recently that the Src kinase Hck interacts directly with Bcr-Abl by a kinase-independent mechanism. Moreover, the inhibition of the Hck kinase seems to block some of the transforming effects of Bcr-Abl. To identify the binding domains mediating this interaction of Hck with Bcr-Abl, we co-expressed different plasmid and baculovirus vectors containing mutants or single domains of Bcr-Abl and/or Hck in COS7 and Sf9 cells. At least four independent binding regions for Hck were identified in Bcr-Abl, one in Bcr, one in the region comprising the SH3 and SH2 domain of Abl, one in the SH1 domain of Abl, and one in the C-terminal domain of Abl. In the Hck kinase, deletion of the SH2 and/or the SH3 region abolished binding to Bcr-Abl. In contrast, deletion of the Hck SH1 domain enhanced binding of Hck to Abl and Bcr-Abl. In conclusion, the results indicate that the interaction of Bcr-Abl with Hck is mediated by a novel, complex mechanism that involves multiple domains of Bcr-Abl and the SH2 and SH3 domains of Hck.
Stanglmaier
M
M
GSF - National Institute of Health and Environment, Klinische Kooperationsgruppe für Gentherapie, Marchioninistrasse 25, 81377 München, Germany.
Warmuth
M
M
Kleinlein
I
I
Reis
S
S
Hallek
M
M
D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D017931:DNA Primers; D016044:Fusion Proteins, bcr-abl; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051572:Proto-Oncogene Proteins c-hck; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D018411:Spodoptera; D014162:Transfection
D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; C496631:HCK protein, human; D051572:Proto-Oncogene Proteins c-hck