| SYNTHESIS |
tRNA promotes translational accuracy Protein biosynthesis is subject to rigorous quality control to prevent missense errors, but the mechanisms to achieve this goal are not yet totally understood. Luisa Cochella and Rachel Green at Johns Hopkins University School of Medicine have now found that tRNAs play an unexpectedly active role in the quality-control process (Science 2005, 308, 1178). Each tRNA is supplied to the ribosome as a complex that must be dismantled before translation can proceed, providing a "proofreading" delay that gives mismatched tRNA extra time to dissociate from the ribosome. The fidelity of translation is further enhanced by ribosome conformational changes induced by tRNA binding, a process called "induced fit." Cochella and Green find that the physical basis for induced fit depends on active conformational contributions made by tRNA upon binding. The study makes it "increasingly clear that, far from being a rigid and passive substrate, tRNA has coevolved with the ribosome to allow the close and dynamic interplay required for the fidelity and speed of translation," a Science commentary notes |
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