CHARACTERIZATION OF IRON(II).BLEOMYCIN-MEDIATED RNA STRAND SCISSION
CHARACTERIZATION OF IRON(II).BLEOMYCIN-MEDIATED RNA STRAND SCISSION
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DOI：
10.1021/bi00067a019
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发表时间：
1993-04-27
期刊：
影响因子：
2.9
通讯作者：
HECHT, SM
中科院分区：
文献类型：
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作者：
HOLMES, CE;CARTER, BJ;HECHT, SM
进一步表征了铁(II).博来霉素介导RNA降解的能力。在微摩尔浓度下，Fe(II).BLM 可有效裂解大肠杆菌 tRNA1His 和粟酒裂殖酵母琥珀抑制 tRNA 构建体。相反，大肠杆菌 tRNA(Cys) 和酵母线粒体 tRNA(Asp) 和 tRNA(f)Met 前体不是 Fe(II).BLM 的底物。酵母 5S 核糖体 RNA 也被证明是 Fe(II).BLM 切割的良好底物。由于 HIV-1 逆转录酶 mRNA 先前已被证明可被 Fe.BLM 降解（Carter 等人，1990a），因此三大类 RNA 的成员现在已被证明会经历 Fe.BLM 介导的链断裂。对于每种底物 RNA，切割发生在该底物特有的位点。尽管 RNA 裂解发生在许多序列上，但 5'-G-pyr-3' 位点最为突出。同样，虽然在预期为双链的区域以及单链区域中注意到裂解，但在单链区域和双链区域之间的连接处注意到不成比例数量的裂解。早期研究发现，RNA 裂解比 DNA 裂解具有更高的选择性，此外，当 RNA 裂解在 Mg2+、亚精胺和 NaCl 等试剂存在下进行时，裂解的选择性进一步增强。许多 RNA 分子的高度选择性和高效切割强化了我们之前的建议，即 RNA 可能构成博莱霉素的治疗相关靶标。
The ability of iron(II).bleomycin to mediate RNA degradation was further characterized. At micromolar concentrations, Fe(II).BLM was shown to effect cleavage of Escherichia coli tRNA1His and a Schizosaccharomyces pombe amber suppressor tRNA construct in an efficient fashion. In contrast, E. coli tRNA(Cys) and yeast mitochondrial tRNA(Asp) and tRNA(f)Met precursors were not substrates for Fe(II).BLM. Also shown to be a good substrate for cleavage by Fe(II).BLM was yeast 5S ribosomal RNA. Since HIV-1 reverse transcriptase mRNA has previously been shown to be degraded by Fe.BLM (Carter et al., 1990a), members of the three major classes of RNA have now been shown to undergo Fe.BLM-mediated strand scission. For each of the substrate RNAs, cleavage occurred at sites unique to that substrate. Although RNA cleavage occurred at numerous sequences, 5'-G-pyr-3' sites were prominent. Likewise, while cleavage was noted in regions anticipated to be double-stranded, as well as in single-stranded regions, a disproportionate number of cleavages were noted at the junction between single- and double-stranded regions. As found in earlier studies, RNA cleavage was much more selective than DNA cleavage, Further, when RNA cleavage was carried out in the presence of reagents such as Mg2+, spermidine, and NaCl, the selectivity of cleavage was further enhanced. The highly selective and efficient cleavage of a number of RNA molecules reinforces our earlier suggestion that RNA may constitute a therapeutically relevant target for bleomycin.