Bidnenko Vladimir, Ehrlich S Dusko, Michel Bénédicte
Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy en Josas, France.
EMBO J. 2002 Jul 15;21(14):3898-907. doi: 10.1093/emboj/cdf369.
Replication fork arrest is a source of genome re arrangements, and the recombinogenic properties of blocked forks are likely to depend on the cause of blockage. Here we study the fate of replication forks blocked at natural replication arrest sites. For this purpose, Escherichia coli replication terminator sequences Ter were placed at ectopic positions on the bacterial chromosome. The resulting strain requires recombinational repair for viability, but replication forks blocked at Ter are not broken. Linear DNA molecules are formed upon arrival of a second round of replication forks that copy the DNA strands of the first blocked forks to the end. A model that accounts for the requirement for homologous recombination for viability in spite of the lack of chromosome breakage is proposed. This work shows that natural and accidental replication arrests sites are processed differently.
复制叉停滞是基因组重排的一个来源，而受阻复制叉的重组特性可能取决于阻滞的原因。在这里，我们研究了在天然复制停滞位点受阻的复制叉的命运。为此，将大肠杆菌复制终止序列Ter置于细菌染色体的异位位置。产生的菌株需要重组修复才能存活，但在Ter处受阻的复制叉不会断裂。第二轮复制叉到达时会形成线性DNA分子，这些复制叉将第一个受阻复制叉的DNA链复制到末端。我们提出了一个模型，该模型解释了尽管没有染色体断裂，但仍需要同源重组才能存活的原因。这项工作表明，天然和偶然的复制停滞位点的处理方式不同。
