Energy coupling in Escherichia coli DNA gyrase: The relationship between nucleotide binding, strand passage, and DNA supercoiling
Energy coupling in Escherichia coli DNA gyrase: The relationship between nucleotide binding, strand passage, and DNA supercoiling
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DOI：
10.1021/bi952433y
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发表时间：
1996-02-06
期刊：
影响因子：
2.9
通讯作者：
Gellert, M
中科院分区：
文献类型：
--
作者：
Bates, AD;ODea, MH;Gellert, M
非水解ATP类似物5'-腺苷基- β， γ -咪啶二磷酸（ADPNP）与大肠杆菌DNA旋转酶结合可导致DNA的有限非催化超卷曲。在这里，我们研究了ADPNP结合与正或负超卷曲质粒DNA或小DNA环的连接数变化之间的偶联效率，偶联效率从100%（每个旋转酶四聚体的δ Lk = -2），在某些反应条件下，正超卷曲底物的化学计量学I)与中等负超卷曲底物（sigma = -0.046）或小圆形底物的化学计量学I)的值低得无法检测。此外，ADPNP与gyase -DNA复合物结合的速率也取决于DNA的拓扑状态；先前观察到的ADPNP与螺旋酶与线性DNA复合物的缓慢结合在底物DNA负超螺旋时加速了16倍，这表明核苷酸结合域和DNA结合域之间存在独立于链传递过程的功能相互作用。对正常的atp依赖的酶的超卷曲反应的含义进行了考虑，并讨论了目前的DNA旋切酶作用的机制模型和酶的可能的体内作用的结果。
Binding of the nonhydrolyzable ATP analogue 5'-adenylyl-beta,gamma-imidodiphosphate (ADPNP) to Escherichia coli DNA gyrase can lead to a limited noncatalytic supercoiling of DNA, Here we examine the efficiency of coupling between ADPNP binding and the change in linking number either of positively or negatively supercoiled plasmid DNA or of small DNA circles, The coupling efficiency varies from 100% (Delta Lk = -2 per gyrase tetramer, a stoichiometry of I) with positively supercoiled substrates under certain reaction conditions to an undetectably low value with moderately negatively supercoiled substrates (sigma = -0.046) or small circular substrates. Furthermore, the rate of ADPNP binding to the gyrase-DNA complex is also dependent on the topological state of the DNA; the previously observed slow binding of ADPNP to the complex of gyrase with linear DNA is accelerated 16-fold when the substrate DNA is negatively supercoiled, suggesting a functional interaction between the nucleotide-binding and DNA-binding domains which is independent of the strand-passage process. The implications for the normal ATP-dependent supercoiling reaction of the enzyme are considered and the results discussed in terms of current mechanistic models for DNA gyrase action and the possible in vivo roles of the enzyme.