Research Article

Structural insight into precursor tRNA processing by yeast ribonuclease P

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Science  27 Sep 2018:
eaat6678
DOI: 10.1126/science.aat6678

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Abstract

Ribonuclease P (RNase P) is a universal ribozyme responsible for processing the 5′-leader of pre-tRNA. Here we report the 3.5-Å cryo-EM structures of Saccharomyces cerevisiae RNase P alone and in complex with pre-tRNAPhe. The protein components form a hook-shaped architecture that wraps around the RNA and stabilizes RNase P into a “measuring device” with two fixed anchors that recognize the L-shaped pre-tRNA. A universally conserved uridine nucleobase and phosphate backbone in the catalytic center together with the scissile phosphate and the O3′ leaving group of pre-tRNA jointly coordinate two catalytic magnesium ions. Binding of pre-tRNA induces a conformational change in the catalytic center that is required for catalysis. Moreover, simulation analysis suggests a two-metal-ion SN2 reaction pathway of pre-tRNA cleavage. These results not only reveal the architecture of yeast RNase P but also provide a molecular basis of how the 5′-leader of pre-tRNA is processed by eukaryotic RNase P.

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