Site-specific cleavage of RNA by Fe(II).bleomycin.
Bleomycin is an antitumor agent whose activity has long been thought to derive from its ability to degrade DNA. Recent findings suggest that cellular RNA may be a therapeutically relevant locus. At micromolar concentrations, Fe(II)-bleomycin readily cleaved a Bacillus subtilis tRNAHis precursor in a highly selective fashion, but Escherichia coli tRNA(Tyr) precursor was largely unaffected even under more forcing conditions. Other substrates included an RNA transcript encoding a large segment of the reverse transcriptase from human immunodeficiency virus 1. RNA cleavage was oxidative, approximately 10-fold more selective than DNA cleavage, and largely unaffected by nonsubstrate RNAs. RNA sequence analysis suggested recognition of RNA tertiary structure, rather than recognition of specific sequences; subsets of nucleotides at the junction of single- and double-stranded regions were especially susceptible to cleavage. The ready accessibility of cellular RNAs to xenobiotic agents, the high selectivity of bleomycin action on RNAs, and the paucity of mechanisms for RNA repair suggest that RNA may be a therapeutically relevant target for bleomycin.
Department of Chemistry, University of Virginia, Charlottesville 22901.
B J
BJ
Carter
E
E
de Vroom
E C
EC
Long
G A
GA
van der Marel
J H
JH
van Boom
S M
SM
Hecht
D001412:Bacillus subtilis / Q000235:genetics; D001483:Base Sequence; D001761:Bleomycin / Q000494:pharmacology* / Q000031:analogs & derivatives; D004926:Escherichia coli / Q000235:genetics; D007700:Kinetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D012354:RNA, Transfer, His / Q000235:genetics / Q000378:metabolism*; D012365:RNA, Transfer, Tyr / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D012354:RNA, Transfer, His; D012365:RNA, Transfer, Tyr; C023503:iron bleomycin; D001761:Bleomycin; D012313:RNA