Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, United Kingdom.
DNA Repair (Amst). 2010 Mar 2;9(3):210-23. doi: 10.1016/j.dnarep.2009.12.014. Epub 2010 Jan 25.
The RecG protein of Escherichia coli is a double-stranded DNA translocase that unwinds a variety of branched DNAs in vitro, including Holliday junctions, replication forks, D-loops and R-loops. Coupled with the reported pleiotropy of recG mutations, this broad range of potential targets has made it hard to pin down what the protein does in vivo, though roles in recombination and replication fork repair have been suggested. However, recent studies suggest that RecG provides a more general defence against pathological DNA replication. We have postulated that this is achieved through the ability of RecG to eliminate substrates that the replication restart protein, PriA, could otherwise exploit to re-replicate the chromosome. Without RecG, PriA triggers a cascade of events that interfere with the duplication and segregation of chromosomes. Here we review the studies that led us to this idea and to conclude that RecG may be both a specialist activity and a general guardian of the genome.
大肠杆菌的 RecG 蛋白是一种双链 DNA 易位酶，可在体外解开多种分支 DNA，包括 Holliday 连接点、复制叉、D 环和 R 环。再加上报告中 RecG 突变的多效性，这种广泛的潜在靶点使得很难确定该蛋白在体内的作用，尽管已经提出了其在重组和复制叉修复中的作用。然而，最近的研究表明，RecG 提供了一种针对病理性 DNA 复制的更普遍的防御机制。我们假设，这是通过 RecG 消除复制起始蛋白 PriA 可能利用的底物来重新复制染色体的能力来实现的。没有 RecG，PriA 会引发一系列干扰染色体复制和分离的事件。在这里，我们回顾了导致我们得出这一观点的研究，并得出结论，RecG 可能既是一种专门的活性酶，也是基因组的一般守护者。
