A single amino acid exchange inverts susceptibility of related receptor tyrosine kinases for the ATP site inhibitor STI-571.
The tyrosine kinase inhibitor STI-571 potently blocks BCR-Abl, platelet-derived growth factor (PDGF) alpha- and beta-receptors, and c-Kit kinase activity. Flt3, a receptor tyrosine kinase closely related to PDGF receptors and c-Kit is, however, not inhibited by STI-571. Sequence alignments of different kinases and indications from the crystal structure of the STI-571 Abl kinase complex revealed amino acid residues that are probably crucial for this activity profile. It was predicted that Flt3 Phe-691 in the beta5 strand may sterically prevent interaction with STI-571. The point mutants Flt3 F691T and PDGFbeta-receptor T681F were constructed, and kinase assays showed that the Flt3 mutant but not the PDGFbeta-receptor mutant is inhibited by STI-571. Docking of STI-571 into computer models of the PDGFbeta-receptor and Flt3 kinase domains and comparison with the crystal structure of the STI-571 Abl kinase complex indicated very similar binding sites among the three nonphosphorylated kinases, suggesting corresponding courses of their Asp-Phe-Gly motifs and activation loops. Accordingly, we observed reduced sensitivity of preactivated compared with nonactivated PDGFR-beta for the inhibition by STI-571. Courses of the activation loop that collide with STI-571 binding explain its inactivity at other kinases as the insulin receptor. The binding site models of PDGFR-beta and Flt3 were applied to predict structural approaches for more selective PDGFbeta-receptor inhibitors.
Böhmer
Frank D
FD
Research Unit Molecular Cell Biology, Medical Faculty, Friedrich Schiller University, D-07747 Jena, Germany. i5frbo@rz.uni-jena.de
Karagyozov
Luchezar
L
Uecker
Andrea
A
Serve
Hubert
H
Botzki
Alexander
A
Mahboobi
Siavosh
S
Dove
Stefan
S
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001549:Benzamides; D001665:Binding Sites / Q000235:genetics; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000068877:Imatinib Mesylate; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010879:Piperazines / Q000494:pharmacology*; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3
D001549:Benzamides; D004791:Enzyme Inhibitors; D010879:Piperazines; D011518:Proto-Oncogene Proteins; D011743:Pyrimidines; D011956:Receptors, Cell Surface; D000068877:Imatinib Mesylate; D000255:Adenosine Triphosphate; D020794:Receptor Protein-Tyrosine Kinases; D020797:Receptor, Platelet-Derived Growth Factor beta; D051941:fms-Like Tyrosine Kinase 3