STUDIES OF FUNCTIONS INVOLVED IN GENETIC RECOMBINATION

反向DNA旋转酶是在嗜热细菌中发现的酶，其 Action在环状DNA中引入了正超级卷曲，代价是 三磷酸腺苷的水解度。前面描述的这类酶有一个 单链多肽链。我们现在已经发现了一个反向回旋酶 嗜热性甲烷甲藻的特殊结构。这 酶有两个亚基，一个具有ATPase活性，另一个具有ATPase活性 执行DNA断裂-重聚步骤。此功能分区是 与真细菌DNA旋转酶相似。 对大肠杆菌DNA旋转酶的进一步研究表明，偶联 超螺旋和核苷酸三磷酸消耗之间的关系取决于 DNA最初的超级卷曲。如果满足以下条件，则可以获得紧耦合 DNA最初是正超级卷曲的。

Reverse DNA gyrases are enzymes found in thermophilic bacteria, whose action introduces positive supercoiling into circular DNA at the expense of ATP hydrolysis. Previously described enzymes of this class have a single polypeptide chain. We have now found a reverse gyrase with an unusual structure in the hyperthermophile Methanopyrus kandleri. This enzyme has two subunits, one having the ATPase activity while the other carries out the DNA breakage-reunion step. This functional partition is similar to that of the eubacterial DNA gyrases. Further studies of E. coli DNA gyrase have shown that the coupling between supercoiling and nucleotide triphosphate consumption depends on the initial supercoiling of the DNA. Tight coupling can be obtained if the DNA is initially positively supercoiled.