White M F, Lilley D M
Department of Biochemistry, The University, Dundee, UK.
J Mol Biol. 1996 Mar 29;257(2):330-41. doi: 10.1006/jmbi.1996.0166.
CCE1 is a DNA junction-resolving enzyme involved in the resolution of recombining mitochondrial DNA in Saccharomyces cerevisiae. The CCE1 gene was cloned by PCR, and the expressed protein purified to homogeneity. CCE1 was found to bind to four-way DNA junctions, with a strong structural selectivity. The enzyme binds DNA junctions as a dimer, with slow subunit exchange occurring in free solution. While CCE1 binds equally to synthetic four-way DNA junctions of any sequence, it exhibits pronounced sequence-selectivity in cleavage. Both fixed junctions and those capable of branch migration can be cleaved, with a preference for cleavage at the sequence 5'CT/. Cleavage of junctions tethered to adopt specific stacking isomers demonstrated that the target sequences are cleaved fivefold faster when located on a continuous strand compared to an exchanging strand.
CCE1是一种参与酿酒酵母中线粒体DNA重组解析的DNA连接点解析酶。通过PCR克隆了CCE1基因，并将表达的蛋白纯化至同质。发现CCE1以强烈的结构选择性结合四链DNA连接点。该酶以二聚体形式结合DNA连接点，在游离溶液中发生缓慢的亚基交换。虽然CCE1对任何序列的合成四链DNA连接点都能同等结合，但在切割时表现出明显的序列选择性。固定连接点和能够进行分支迁移的连接点都可以被切割，优先在5'CT/序列处切割。对采用特定堆积异构体的连接点进行切割表明，与交换链相比，当目标序列位于连续链上时，其切割速度快五倍。
