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A DNA enzyme that cleaves RNABACKGROUND: Several types of RNA enzymes (ribozymes) have been identified in biological systems and generated in the laboratory. Considering the variety of known RNA enzymes and the similarity of DNA and RNA, it is reasonable to imagine that DNA might be able to function as an enzyme as well. No such DNA enzyme has been found in nature, however. We set out to identify a metal-dependent DNA enzyme using in vitro selection methodology. RESULTS: Beginning with a population of 10(14) DNAs containing 50 random nucleotides, we carried out five successive rounds of selective amplification, enriching for individuals that best promote the Pb(2+)-dependent cleavage of a target ribonucleoside 3'-O-P bond embedded within an otherwise all-DNA sequence. By the fifth round, the population as a whole carried out this reaction at a rate of 0.2 min-1. Based on the sequence of 20 individuals isolated from this population, we designed a simplified version of the catalytic domain that operates in an intermolecular context with a turnover rate of 1 min-1. This rate is about 10(5)-fold increased compared to the uncatalyzed reaction. CONCLUSIONS: Using in vitro selection techniques, we obtained a DNA enzyme that catalyzes the Pb(2+)-dependent cleavage of an RNA phosphoester in a reaction that proceeds with rapid turnover. The catalytic rate compares favorably to that of known RNA enzymes. We expect that other examples of DNA enzymes will soon be forthcoming.
Document ID
20040172795
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Breaker, R. R.
(Scripps Research Institute La Jolla, CA 92037, United States)
Joyce, G. F.
Hoyce, G. F.
Date Acquired
August 22, 2013
Publication Date
December 1, 1994
Publication Information
Publication: Chemistry & biology
Volume: 1
Issue: 4
ISSN: 1074-5521
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

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