In the presence of subunit A inhibitors DNA gyrase cleaves DNA fragments as short as 20 bp at specific sites

被引:21
作者
Gmunder, H
Kuratli, K
Keck, W
机构
[1] F. Hoffmann-La Roche Ltd., Pharmaceutical Res. Preclin. I.
关键词
D O I
10.1093/nar/25.3.604
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
A key step in the supercoiling reaction is the DNA gyrase-mediated cleavage and religation step of double-stranded DNA. Footprinting studies suggest that the DNA gyrase binding site is 100-150 bp long and that the DNA is wrapped around the enzyme with the cleavage site located near the center of the fragment. Subunit A inhibitors interrupt this cleavage and resealing cycle and result in cleavage occurring at preferred sites. We have been able to show that even a 30 bp DNA fragment containing a 20 bp preferred cleavage sequence from the pBR322 plasmid was a substrate for the DNA gyrase-mediated cleavage reaction in the presence of inhibitors. This DNA fragment was cleaved, although with reduced efficiency, at the same sites as a 122 bp DNA fragment. A 20 bp DNA fragment was cleaved with low efficiency at one of these sites and a 10 bp DNA fragment was no longer a substrate. We therefore propose that subunit A inhibitors interact with DNA at inhibitor-specific positions, thus determining cleavage sites by forming ternary complexes between DNA, inhibitors and DNA gyrase.
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页码:604 / 610
页数:7
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