Molecular biological analysis of sequence-specific DNA recognition and cleavage by metallobleomycins |
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Authors: | J Kuwahara Y Sugiura |
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Affiliation: | Faculty of Pharmaceutical Sciences, Kyoto University, Japan. |
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Abstract: | The DNase I footprinting analysis shows binding sites of approximately two or three base pairs, in particular 5'-XGC sequences, for the green-colored Co(III) and fully oxidized Fe(III) complexes of bleomycin (BLM). In contrast to covalent attachment of guanine N-7 with aflatoxin B1 or dimethyl sulfate, the modification of guanine 2-amino group with anthramycin remarkably inhibits the DNA cleavages at 5'-GC and 5'-GT sites by the iron and cobalt complex systems of BLM. The present results strongly indicate that metallobleomycin binds in minor groove of B-DNA and that the 2-amino group of guanine adjacent to 5'-side of the cleaved pyrimidine base is one key element of specific 5'-GC or 5'-GT recognition by metallobleomycin. On the basis of these experimental data, possible binding mode of metallobleomycin in B-DNA helix has been proposed by computer-constructed model building. |
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