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Cleavage of tRNA by Fe(II)-bleomycin
A Hüttenhofer1, S Hudson, H F Noller
1Sinsheimer Laboratories, University of California, Santa Cruz 95064.
The Journal of Biological Chemistry
|December 5, 1992
Summary
Fe(II)-bleomycin cleaves yeast tRNA(Phe) at specific sites without magnesium ions. However, magnesium ions prevent this cleavage, suggesting Fe(II)-bleomycin
Area of Science:
- Biochemistry
- Molecular Biology
- RNA Structure and Function
Background:
- Fe(II)-bleomycin is a chemotherapeutic agent.
- Yeast tRNA(Phe) has a known three-dimensional structure.
Purpose of the Study:
- To investigate the action of Fe(II)-bleomycin on yeast tRNA(Phe).
- To determine the effect of magnesium ions on Fe(II)-bleomycin-induced RNA cleavage.
Main Methods:
- Cleavage assays using Fe(II)-bleomycin on yeast tRNA(Phe) and a tRNA fragment.
- Varying magnesium ion concentrations.
- Comparison with DNA analog cleavage.
Main Results:
- Fe(II)-bleomycin preferentially cleaved yeast tRNA(Phe) at A31 and G53 in the absence of Mg2+.
- Cleavage was abolished at physiological Mg2+ concentrations (> 0.5 mM).
- Mg2+ inhibition was not observed with DNA analogs, and cleavage site specificities differed between RNA and DNA.
Conclusions:
- Tight Mg2+ binding to tRNA likely excludes productive interactions with Fe(II)-bleomycin.
- Mg2+-dependent tertiary interactions are not responsible for the loss of cleavage.
- RNA cleavage by Fe(II)-bleomycin is unlikely to be therapeutically relevant.