Structural basis of oncogenic activation caused by point mutations in the kinase domain of the MET proto-oncogene: Modeling studies

Missense mutations in the tyrosine kinase domain of the MET proto-oncogene occur in selected cases of papillary renal carcinoma. in biochemical and bi ological assays, these mutations produced constitutive activation of the ME T kinase and led to tumor formation in nude mice. Some mutations caused tra nsformation of NM 3T3 cells. To elucidate the mechanism of ligand-independe nt MET kinase activation by point mutations, we constructed several 3D mode ls of the wild-type and mutated MET catalytic core domains, Analysis of the se structures showed that some mutations (e,g,, V1110I, Y1248H/D/C, M1268T) directly alter contacts between residues from the activation loop in its i nhibitory conformation and those from the main body of the catalytic domain ; others (e.g., M1149T, L1213V) increase flexibility at the critical paints of the tertiary structure and facilitate subdomain movements, Mutation D12 46N plays a role in stabilizing the active form of the enzyme, Mutation M12 68T affects the S+1 and S+3 substrate-binding pockets, Models implicate tha t although these changes do not compromise the affinity toward the C-termin al autophosphorylation site of the MET protein, they allow for binding of t he substrate for the c-Abl tyrosine kinase. We provide biochemical data sup porting this observation, Mutation L1213V affects the conformation of Tyr12 12 in the active form of MET. Several somatic mutations are clustered at th e surface of the catalytic domain in close vicinity of the probable locatio n of the MET C-terminal docking site for cytoplasmic effecters, Proteins 20 01;44:32-43. (C) 2001 Wiley-Liss, Inc.*.