The Mechanism for Activation of GTP Hydrolysis on the Ribosome

Abstract

A Likely Conformation At several stages of protein synthesis, guanosine triphosphate hydrolyzing enzymes (GTPases) interact with the ribosome, and GTP hydrolysis is coupled to progression of synthesis. Voorhees et al. (p. 835 ) have determined a 3.2-resolution structure of the GTPase, elongation factor Tu, which delivers amino-acyl transfer RNA (tRNA) to the ribosome. The GTPase and tRNA were bound to the ribosome and were stalled in an active conformation by a GTP analog. The structure revealed that activation of the enzyme only required small changes in conformation to move a catalytic histidine into the correct position for hydrolysis. A similar mechanism likely applies to the activation of other translational GTPases.