Prof. Carla Mattos, North Carolina State University

Intrinsic hydrolysis in Ras functions through an allosteric switch in the Ras/Raf/MEK/ERK signal transduction pathway

Biochemistry Seminar Series

Ras is a key protein in cellular signal transduction. Mutants of G12 and Q61 impair GTPase activity and are found prominently in cancers. In wild type an allosteric switch promotes disorder to order transition in switch II, placing Q61 near water 189 in the active site. We show that the “on” and ‘off” conformations of the allosteric switch can also be attained in RasG12V and RasQ61L. The “on” state in both mutants disallows water 189 and proper placing of Q61 (or lack thereof). While the “off” state in RasG12V is disordered like wild type, that in RasQ61L stabilizes an anticatalytic conformation in the presence of Raf. Using a combination of structural analysis, hydrolysis rates in the presence and absence of Raf and experiments in NIH-3T3 cells we link the allosteric switch to the control of signaling in the Ras/Raf/MEK/ERK pathway. Furthermore, we have captured a transition state mimic for the intrinsic hydrolysis reaction using AlF3 bound to an allosteric site mutant that stabilizes the “on” state of the allosteric switch.

For more information contact Prof. Raquel Lieberman (404-385-3663).