In situ selectivity profiling and crystal structure of SML-8-73-1, an active site inhibitor of oncogenic K-Ras G12C

• DOI: 10.1073/pnas.1404639111
• Publication Date: 2014-06-03T06:56:28Z
• Authors: John C. Hunter; Deepak Gurbani; Scott B. Ficarro; Martin A. Carrasco; Sang Min Lim; Hwan Geun Choi; Ting Xie; Jarrod A. Marto; Zhe Chen; Nathanael S. Gray; Kenneth D. Westover
• Keywords: Models, Molecular; Proteomics; 0301 basic medicine; Binding Sites; Protein Conformation; Biotin; Crystallography, X-Ray; Ligands; Guanosine Diphosphate; GTP Phosphohydrolases; Phosphatidylinositol 3-Kinases; 03 medical and health sciences; Genes, ras; GTP-Binding Proteins; Catalytic Domain; Acetamides; Mutation; Humans; Guanosine Triphosphate; Conserved Sequence; Protein Binding; Signal Transduction

Significance SML-8-73-1 (SML) is the first example, to our knowledge, of a GTP-competitive inhibitor of V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (K-Ras). A high-resolution structure of K-Ras G12C bound to SML shows K-Ras in an inactive conformation. In situ proteomic-based chemical profiling of SML demonstrates that SML is highly selective for K-Ras G12C over other small GTPases. A novel chemosensor-based assay allows measurement of covalent reaction rates between K-Ras G12C and SML and enables characterization of this reaction in the context of millimolar concentrations of GTP and GDP, well in exccss of what is found in living cells. These results demonstrate that even in the presence of high concentrations of GTP and GDP, SML is able to exchange into the GN site.