Jones J M, Nakai H
Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, 331 Basic Science Building, 3900 Reservoir Road NW, Washington DC 20007, USA.
Mol Microbiol. 2000 May;36(3):519-27. doi: 10.1046/j.1365-2958.2000.01888.x.
The initiation of DNA synthesis on forked DNA templates is a vital process in the replication and maintenance of cellular chromosomes. Two proteins that promote replisome assembly on DNA forks have so far been identified. In phage T4 development the gene 59 protein (gp59) assembles replisomes at D-loops, the sites of homologous strand exchange. Bacterial PriA protein plays an analogous function, most probably restarting replication after replication fork arrest with the aid of homologous recombination proteins, and PriA is also required for phage Mu replication by transposition. Gp59 and PriA exhibit similar DNA fork binding activities, but PriA also has a 3' to 5' helicase activity that can promote duplex opening for replisome assembly. The helicase activity allows PriA's repertoire of templates to be more diverse than that of gp59. It may give PriA the versatility to restart DNA replication without recombination on arrested replication forks that lack appropriate duplex openings.
在叉状DNA模板上启动DNA合成是细胞染色体复制和维持过程中的一个关键过程。到目前为止，已鉴定出两种促进DNA叉上复制体组装的蛋白质。在噬菌体T4发育过程中，基因59蛋白（gp59）在D环（同源链交换位点）组装复制体。细菌PriA蛋白具有类似的功能，很可能在复制叉停滞后借助同源重组蛋白重启复制，并且噬菌体Mu通过转座进行复制也需要PriA。Gp59和PriA表现出相似的DNA叉结合活性，但PriA还具有3'到5'解旋酶活性，可促进双链打开以进行复制体组装。解旋酶活性使PriA的模板库比gp59的更多样化。这可能赋予PriA在缺乏合适双链开口的停滞复制叉上无需重组即可重启DNA复制的多功能性。
