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Updated: Jul 14, 2026
08:34
An Engineered Split-TET2 Enzyme for Chemical-inducible DNA Hydroxymethylation and Epigenetic Remodeling
Published on: December 18, 2017
A small metalloribozyme with a two-step mechanism.
1Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309.
Nature
|August 13, 1992
Summary
Lead ions (Pb2+) rapidly cleave specific RNA molecules with an internal loop, forming a 3' phosphomonoester. This RNA-catalyzed reaction mimics protein ribonuclease mechanisms previously unobserved in RNA.
Area of Science:
- Biochemistry
- Molecular Biology
- RNA Catalysis
Background:
- Ribonucleases (RNases) are enzymes that catalyze the degradation of RNA.
- Many protein RNases employ a two-step catalytic mechanism involving a cyclic phosphodiester intermediate.
- RNA molecules themselves can act as catalysts (ribozymes), but their catalytic mechanisms are diverse and still being discovered.
Purpose of the Study:
- To investigate the catalytic activity of a specific RNA molecule with an asymmetric internal loop.
- To elucidate the reaction mechanism of RNA-mediated cleavage.
- To determine if RNA catalysis can mimic protein ribonuclease mechanisms.
Main Methods:
- In vitro cleavage assays using a synthetic RNA molecule containing an asymmetric internal loop.
- Characterization of cleavage products using gel electrophoresis and mass spectrometry.
- Kinetic analysis of the cleavage reaction in the presence of lead (Pb2+) and magnesium (Mg2+) ions.
Main Results:
- The RNA molecule was rapidly and specifically cleaved by Pb2+ in the presence of Mg2+.
- The 5' cleavage product consistently terminated with a 3' phosphomonoester.
- A 2',3'-cyclic phosphodiester reaction intermediate was identified, indicating a two-step mechanism.
- This mechanism mirrors that of many protein ribonucleases.
Conclusions:
- RNA molecules can catalyze specific RNA cleavage via a mechanism previously thought to be exclusive to protein enzymes.
- The identified RNA molecule acts as a self-cleaving ribozyme with a novel catalytic mechanism.
- This finding expands the known repertoire of ribozyme functions and catalytic strategies.
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