A top-half tDNA minihelix is a good substrate for the eubacterial CCA- adding enzyme

Pei Yong Shi, Alan M. Weiner, Nancy Maizels

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59 Scopus citations


The CCA-adding enzyme [ATP(CTP):tRNA nucleotidyltransferase] catalyzes the addition and regeneration of the 3'-terminal CCA sequence of tRNAs. We show that the CCA-adding enzyme will specifically add a CCA terminus to synthetic full-length tDNA and to DNA oligonucleotides corresponding to the 'top half' of tRNA-the acceptor stem and TψC stem-loop of tRNA. CCA addition to the top half tDNA minihelices requires a 2' as well as a 3' OH at the 3' terminus of the tDNA. Addition also depends on the length of the base paired stem, and is facilitated by, but is not dependent upon, the presence of a TψC loop. These results provide further evidence for independent functions of the top and bottom halves of tRNA, and support the hypothesis that these two structurally distinct and functionally independent domains evolved independently.

Original languageEnglish (US)
Pages (from-to)276-284
Number of pages9
Issue number3
StatePublished - Mar 1 1998



  • Nucleotidyltransferase
  • tRNA

ASJC Scopus subject areas

  • Molecular Biology

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