Interaction between Ras and the two Ras‐Binding Domains of Raf kinase

The interaction between Ras and Raf kinase at the membrane promotes cell proliferation through the mitogen activated protein kinase (MAPK) pathway. Ras mutations drive 20% of all human cancers and despite great efforts, there are currently no drugs targeting Ras. Raf interacts with Ras via its two N‐terminal Ras‐binding domains: the Ras‐binding domain (RBD) and the cysteine‐rich domain. Binding of both the Raf‐RBD and CRD are required for Ras‐mediated activation of Raf kinase, however, the mechanism that results in the activation of the C‐terminal Raf kinase domain remains unknown. Here we present the 2.8 Å crystal structure of Ras in complex with a Raf construct containing both the RBD and CRD, revealing the interface for Raf‐CRD binding. In combination with molecular dynamic simulations, we identify allosteric effects induced by Raf‐CRD binding that stabilize the Ras active site to promote a Ras conformation poised for intrinsic hydrolysis. Support or Funding Information NSF, MCB‐1517295. Northeastern Office of Undergraduate Research and Fellowships