Fe·bleomycin cleaves a transfer RNA precursor and its "transfer DNA" analog at the same major site

Chris E. Holmes, Sidney M. Hecht

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Previously, Fe·bleomycin (BLM) has been shown to mediate RNA cleavage in a fashion more highly selective than that of DNA. Because RNAs often assume secondary and tertiary structures not commonly encountered with DNAs, it was not clear whether the greater selectivity of RNA cleavage was a consequence of differences in the mononucleotide constituents of RNA and DNA, or of the three-dimensional structures of the individual substrates. Accordingly, we prepared a "tDNA" identical in sequence with Bacillus subtilis tRNAHis precursor, the latter of which is known to be a good substrate for Fe(II)·BLM A2 and which undergoes oxidative cleavage predominantly at U35. Remarkably, the tDNA underwent cleavage predominantly at T35. At higher concentrations of Fe(II)·BLM A2, the tDNA was extensively degraded, while the tRNAHis precursor was not. Competition experiments suggested that this was not due to more efficient binding of Fe·BLM to the tDNA; in fact the tRNA precursor appeared to be bound more efficiently. The lesser cleavage of the tRNAHis may be due to limitations in the facility of chemical transformation following Fe·BLM binding, or else to the formation of RNA lesions that do not lead directly to RNA strand scission.

Original languageEnglish (US)
Pages (from-to)25909-25913
Number of pages5
JournalJournal of Biological Chemistry
Issue number34
StatePublished - Dec 5 1993
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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