Komori Kayoko, Fujikane Ryosuke, Shinagawa Hideo, Ishino Yoshizumi
Department of Molecular Biology, Biomolecular Engineering Research Institute, Suita, Osaka, Japan.
Genes Genet Syst. 2002 Aug;77(4):227-41. doi: 10.1266/ggs.77.227.
We identified a novel structure-specific endonuclease in Pyrococcus furiosus. This nuclease contains two distinct domains, which are similar to the DEAH helicase family at the N-terminal two-third and the XPF endonuclease superfamily at the C-terminal one-third of the protein, respectively. The C-terminal domain has an endonuclease activity cleaving the DNA strand at the 5'-side of nicked or flapped positions in the duplex DNA. The nuclease also incises in the proximity of the 5'-side of a branch point in the template strand for leading synthesis in the fork-structured DNA. The N-terminal helicase may work cooperatively to change the fork structure suitable for cleavage by the C-terminal endonuclease. This protein, designated as Hef (helicase-associated endonuclease for fork-structured DNA), may be a prototypical enzyme for resolving stalled forks during DNA replication, as well as working at nucleotide excision repair.
我们在嗜热栖热菌中鉴定出一种新型的结构特异性核酸内切酶。这种核酸内切酶包含两个不同的结构域，在蛋白质的N端三分之二处与DEAH解旋酶家族相似，在C端三分之一处分别与XPF核酸内切酶超家族相似。C端结构域具有核酸内切酶活性，可在双链DNA中切口或侧翼位置的5'侧切割DNA链。该核酸内切酶还可在模板链分支点的5'侧附近进行切割，以引导叉状结构DNA中的合成。N端解旋酶可能协同作用，改变适合C端核酸内切酶切割的叉状结构。这种蛋白质被命名为Hef（叉状结构DNA的解旋酶相关核酸内切酶），可能是一种在DNA复制过程中解决停滞叉状结构的原型酶，同时也在核苷酸切除修复中发挥作用。
