<p>Ribonuclease P (RNase P) is an essential metallonuclease found in all three domains of life. However, the structural basis for the ancient RNase P RNA component acting alone as a ribozyme and catalytic metal-ion chemistry remains unknown. We report a series of cryo-EM structures, at resolutions of 2.8–3.5 Å, of the <i>Geobacillus stearothermophilus</i> RNase P aporibozyme (apoE) in various states of the catalytic cycle. The formation of both the tetraloop/tetraloop-receptor interaction and the interdigitated double T-loop motif in the substrate-specificity domain facilitates substrate binding. The apoE uses two metal ions for catalysis, suggesting a catalytic mechanism and evolutionary importance of the RNase P ribozyme to function without its protein component. Together, our data portray the regulatory RNA-RNA interfaces, dynamic structures, and cation traffic that confer function to a <i>trans-acting</i> ribozyme.</p>

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Structural basis for protein-free catalysis by ribonuclease P ribozyme

  • Yun-Tzai Lee,
  • Maximilia F. S. Degenhardt,
  • Ilias Skeparnias,
  • Szu-Yun Chen,
  • Bapurao A. Bhoge,
  • Sergey G. Tarasov,
  • Marzena A. Dyba,
  • Jinwei Zhang,
  • Jason R. Stagno,
  • Yun-Xing Wang

摘要

Ribonuclease P (RNase P) is an essential metallonuclease found in all three domains of life. However, the structural basis for the ancient RNase P RNA component acting alone as a ribozyme and catalytic metal-ion chemistry remains unknown. We report a series of cryo-EM structures, at resolutions of 2.8–3.5 Å, of the Geobacillus stearothermophilus RNase P aporibozyme (apoE) in various states of the catalytic cycle. The formation of both the tetraloop/tetraloop-receptor interaction and the interdigitated double T-loop motif in the substrate-specificity domain facilitates substrate binding. The apoE uses two metal ions for catalysis, suggesting a catalytic mechanism and evolutionary importance of the RNase P ribozyme to function without its protein component. Together, our data portray the regulatory RNA-RNA interfaces, dynamic structures, and cation traffic that confer function to a trans-acting ribozyme.