MAPPING THE TOPOGRAPHY OF DNA WRAPPED AROUND GYRASE BY NUCLEOLYTIC AND CHEMICAL PROBING OF COMPLEXES OF UNIQUE DNA-SEQUENCES
MAPPING THE TOPOGRAPHY OF DNA WRAPPED AROUND GYRASE BY NUCLEOLYTIC AND CHEMICAL PROBING OF COMPLEXES OF UNIQUE DNA-SEQUENCES
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DOI：
10.1016/0092-8674(81)90435-9
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发表时间：
1981-01-01
期刊：
影响因子：
64.5
通讯作者：
WANG, JC
中科院分区：
文献类型：
--
作者：
KIRKEGAARD, K;WANG, JC
[大肠杆菌] DNA促旋酶和DNA片段的独特序列之间的复合物被用来探测的DNA与核酸酶和硫酸二甲酯的地形。结果表明，145-155 bp DNA片段的侧翼区（每个50 bp [碱基对]大小）对葡萄球菌核酸酶具有抗性，该葡萄球菌核酸酶含有间隔10-11个核苷酸的胰腺DNA酶I敏感位点组。互补链上的相邻DNA酶I敏感位点对通常交错2-4 bp。DNA与促旋酶的结合不能防止DNA被硫酸二甲酯烷基化。螺旋酶-DNA复合物的这些性质让人想起核小体的那些性质，并且共同的潜在结构特征似乎是DNA围绕蛋白质核心的包裹。回旋酶-DNA复合物与核小体的不同之处在于，它必须具有催化DNA链断裂和ATP调节DNA-酶相互作用所必需的特征。有证据表明，葡萄球菌核酸酶耐药DNA片段的中心区域内发生的促旋酶的DNA断裂和重新连接。本文还讨论了这一现象与促旋酶诱导DNA超螺旋机制的关系。加入ATP或其β，γ-酰亚胺类似物对DNA酶I的亲和性模式基本上没有影响，这意味着由核酸酶映射的DNA-酶接触几乎不受ATP诱导的构象变化的影响。
Complexes between [Escherichia coli] DNA gyrase and DNA fragments of unique sequences were used to probe the topography of the DNA with nucleases and dimethyl sulfate. The results indicate that the flanking regions, each 50 bp [base pairs] in size, of a 145-155 bp DNA segment are resistant to staphylococcal nuclease containing groups of pancreatic DNase I-susceptible sites that are spaced 10-11 nucleotides apart. Pairs of adjacent DNase I-sensitive sites on complementary strands are typically staggered by 2-4 bp. The binding of DNA to gyrase confers no protection against alkylation of the DNA by dimethyl sulfate. These properties of the gyrase-DNA complex are reminiscent of those of the nucleosome, and the common underlying structural feature appears to be the wrapping of the DNA around a protein core. The gyrase-DNA complex differs from the nucleosome in that it must possess features necessary for the catalysis of DNA chain breakage and the modulation of the DNA-enzyme interaction by ATP. Evidence that the breakage and rejoining of the DNA by gyrase occur within a central region of the staphylococcal nuclease-resistant DNA segment is presented. The relation of this observation to the mechanism of DNA supercoiling by gyrase is discussed. Addition of ATP or its .beta., .gamma.-imido analog has essentially no effect on the patterns of susceptibilities to DNase I, implying that the DNA-enzyme contacts mapped by the nuclease are little affected by ATP-induced conformational changes.