Experimental Multiple Solvent Crystal Structures Method Applied to WT H‐Ras and the oncogenic mutants G12V and Q61L

The Ras family of GTPases act as ‘molecular switches' to regulate numerous cellular processes. The G12V and Q61L mutants of H‐Ras are two of the most common, highly oncogenic mutations. Recently, we have discovered a structural mechanism of additional allosteric control of the molecular switch. Structural differences in the oncogenic mutants G12V and Q61L force them to respond differently to allosteric activation. Research has shown that the range of conformational diversity is a critical element responsible for functional differences both between Ras family members and between normal and mutant Ras proteins. In this paper, we probe the conformational diversity and ligand binding potential of the GTP form of H‐Ras in the context of the allosteric switch, by applying the Multiple Solvent Crystal Structures method (MSCS) to H‐Ras bound to the nonhydrolyzable GTP analog GppNHp. We present the experimental multiple solvent crystal structure method (MSCS) applied to WT H‐Ras, G12V H‐Ras and Q61L H‐Ras. Comparison of the solvent binding maps of these three proteins clearly delineates the inter‐lobe boundary of the two lobe Ras model. Differences in solvent binding and protein plasticity are related to structural and functional differences between the two oncogenic mutants and suggest new approaches in anti‐cancer targeted drug design efforts.