The Ras/Raf/MEK/ERK signal transduction pathway is a major regulator of cell proliferation activated by Ras-guanosine triphosphate (GTP). The oncogenic mutant RasQ61L is not able to hydrolyze GTP in the presence of Raf and thus is a constitutive acti ...
The Ras/Raf/MEK/ERK signal transduction pathway is a major regulator of cell proliferation activated by Ras-guanosine triphosphate (GTP). The oncogenic mutant RasQ61L is not able to hydrolyze GTP in the presence of Raf and thus is a constitutive activator of this mitogenic pathway. The Ras/Raf interaction is essential for the activation of the Raf kinase domain through a currently unknown mechanism. We present the crystal structures of the Ras-GppNHp/Raf-RBD and RasQ61L-GppNHp/Raf-RBD complexes, which, in combination with MD simulations, reveal differences in allosteric interactions leading from the Ras/Raf interface to the Ras calcium-binding site and to the remote Raf-RBD loop L4. In the presence of Raf, the RasQ61L mutant has a rigid switch II relative to the wild-type and increased flexibility at the interface with switch I, which propagates across Raf-RBD. We show that in addition to local perturbations on Ras, RasQ61L has substantial long-range effects on the Ras allosteric lobe and on Raf-RBD.
Organizational Affiliation:
Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA; Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA. Electronic address: c.mattos@neu.edu.,Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA; Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA.,Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA.,Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA; Department of Human Genetics, Sackler Institute of Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.,Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA.,Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA.
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