Analysis of the activating mutations within the activation loop of leukemia targets Flt-3 and c-Kit based on protein homology modeling.
Molecular modeling provides a mechanistic hypothesis at the molecular level for the constitutive activation recently observed and reported for tyrosine protein kinases Flt-3 and c-Kit. Three-dimensional homology models for the active and inactive forms of these two kinases were made. Comparison of these models at the molecular level reveals that mutations of specific residues located in the activation loop (D835X and 836-deletion in Flt-3; D816V in c-Kit) as well as a 6-base pair (6-bp) insertion at residue 840 in Flt-3 operate in a similar way. Each mutation tends to weaken the forces that maintain the activation-loop folded inwards. None of the mutations are found to particularly stabilize the active state directly. The reason why the equilibrium is shifted towards the gate-open conformation of the protein is because, at least in these models, the mutations are found to critically destabilize the inactive conformational state of the kinase.
Torrent
Maricel
M
Departments of Molecular Systems, Merck Research Laboratories, Merck Co., Sumneytown Pike,West Point, PA 19486, USA. maricel_torrent@merck.com
Rickert
Keith
K
Pan
Bo-Sheng
BS
Sepp-Lorenzino
Laura
L
D020134:Catalytic Domain / Q000235:genetics; D003198:Computer Simulation; D004789:Enzyme Activation / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology* / Q000235:genetics*; D008958:Models, Molecular; D009154:Mutation; D017354:Point Mutation; D011487:Protein Conformation; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D013816:Thermodynamics; D051941:fms-Like Tyrosine Kinase 3
D011518:Proto-Oncogene Proteins; C497970:FLT3 protein, human; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3