White M F, Lilley D M
Department of Biochemistry, University Dundee, UK.
J Mol Biol. 1997 Feb 14;266(1):122-34. doi: 10.1006/jmbi.1996.0795.
Junction-resolving enzymes exhibit structure-selective binding to DNA, but may also manipulate the DNA structure. CCE1 is a junction-resolving enzyme found in the yeast mitochondrion. To facilitate the analysis of the CCE1-junction interaction, we have exploited the sequence dependence of the cleavage reaction to devise a junction that is refractory to cleavage by this enzyme, even in the presence of magnesium ions. On binding to four-way DNA junctions, pure recombinant CCE1 opens the global structure into a 4-fold symmetrical configuration of arms with an open, chemically reactive centre. The structure of the CCE1-junction complex is independent of the sequence of the junction, and of the presence or absence of magnesium or other ions. This and other functional properties of CCE1 are strikingly similar to those of RuvC resolving enzyme of Escherichia coli.
连接点解析酶对DNA具有结构选择性结合，但也可能操纵DNA结构。CCE1是一种存在于酵母线粒体中的连接点解析酶。为便于分析CCE1与连接点的相互作用，我们利用切割反应的序列依赖性设计了一种即使在镁离子存在的情况下也难以被该酶切割的连接点。纯重组CCE1与四链DNA连接点结合时，会将整体结构打开成具有开放化学反应中心的4倍对称臂构型。CCE1-连接点复合物的结构与连接点的序列无关，也与镁离子或其他离子的存在与否无关。CCE1的这一特性及其他功能特性与大肠杆菌的RuvC解析酶极为相似。
