The dynamics of the catalytic site in small GTPases, variations on a common motif

Abstract

Small GTPases control many cellular processes. Their catalytic downregulation by GTPase activating proteins (GAP) is essential. Many structural models of GTPase·GAP complexes obtained by X-ray structural analysis are available nowadays. They reveal important insights into the catalytic site and can suggest important catalytic residues. But this information is static. Time-resolved FTIR spectroscopy can resolve the dynamics of the catalytic site at atomic detail. For the investigation of GAP catalyzed GTPase reactions of small GTPases, the order of events like the action of certain catalytic amino acids, bond breakages and protein conformational changes can be elucidated. This is elaborated for many small GTPases like Ras, Rap, Ran, Rho and Rab and their cognate GAPs. Variations on a common dynamic motif of the catalytic site of small GTPase will be presented.