Analysis of Binding Site Hot Spots on the Surface of Ras GTPase.Buhrman, G., O Connor, C., Zerbe, B., Kearney, B.M., Napoleon, R., Kovrigina, E.A., Vajda, S., Kozakov, D., Kovrigin, E.L., Mattos, C.
(2011) J Mol Biol 413: 773-789
- PubMed: 21945529
- DOI: https://doi.org/10.1016/j.jmb.2011.09.011
- Primary Citation of Related Structures:
3RRY, 3RRZ, 3RS0, 3RS2, 3RS3, 3RS4, 3RS5, 3RS7, 3RSL, 3RSO
- PubMed Abstract:
We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the "off" and "on" allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target.
Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA.