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Evolution in vitro of an RNA enzyme with altered metal dependenceThe Tetrahymena group I ribozyme catalyses a sequence-specific phosphodiester cleavage reaction on an external RNA oligonucleotide substrate in the presence of a divalent metal cation cofactor. This reaction proceeds readily with either Mg2+ or Mn2+, but no detectable reaction has been reported when other divalent cations are used as the sole cofactor. Cations such as Ca2+, Sr2+ and Ba2+ can stabilize the correct folded conformation of the ribozyme, thereby partially alleviating the Mg2+ or Mn2+ requirement. But catalysis by the ribozyme involves coordination of either Mg2+ or Mn2+ at the active site, resulting in an overall requirement for one of these two cations. Here we use an in vitro evolution process to obtain variants of the Tetrahymena ribozyme that are capable of cleaving an RNA substrate in reaction mixtures containing Ca2+ as the divalent cation. These findings extend the range of different chemical environments available to RNA enzymes and illustrate the power of in vitro evolution in generating macromolecular catalysts with desired properties.
Document ID
20050000522
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lehman, N.
(Scripps Research Institute La Jolla, California 92037)
Joyce, G. F.
Date Acquired
August 22, 2013
Publication Date
January 14, 1993
Publication Information
Publication: Nature
Volume: 361
Issue: 6408
ISSN: 0028-0836
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
Non-NASA Center

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