Division of Biosciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK.
Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
Int J Mol Sci. 2021 Jul 25;22(15):7928. doi: 10.3390/ijms22157928.
Termination of DNA replication, the final stage of genome duplication, is surprisingly complex, and failures to bring DNA synthesis to an accurate conclusion can impact genome stability and cell viability. In , termination takes place in a specialised termination area opposite the origin. A 'replication fork trap' is formed by unidirectional fork barriers via the binding of Tus protein to genomic sites. Such a fork trap system is found in some bacterial species, but it appears not to be a general feature of bacterial chromosomes. The biochemical properties of fork trap systems have been extensively characterised, but little is known about their precise physiological roles. In this study, we compare locations and distributions of terminator sites in genomes across all phylogenetic groups, including . Our analysis shows that all sites are highly conserved in , with slightly more variability in the genomes. Our sequence analysis of sites and Tus proteins shows that the fork trap is likely to be active in all strains investigated. In addition, our analysis shows that the chromosome dimer resolution site is consistently located between the innermost sites, even if rearrangements have changed the location of the innermost termination area. Our data further support the idea that the replication fork trap has an important physiological role that provides an evolutionary advantage.
DNA 复制的终止是基因组复制的最后阶段，它的过程出人意料地复杂，而如果不能准确地完成 DNA 合成，就会影响基因组的稳定性和细胞的存活能力。在 中，终止发生在与起点相对的专门的终止区域。通过 Tus 蛋白与基因组 位点的结合，单向叉状障碍形成了一个“复制叉陷阱”。这种叉状陷阱系统存在于一些细菌物种中，但似乎不是细菌染色体的普遍特征。叉状陷阱系统的生化特性已经得到了广泛的研究，但对于其确切的生理作用却知之甚少。在这项研究中，我们比较了所有进化群系的 基因组中 终止子位点的位置和分布，包括 。我们的分析表明，所有 位点在 中都高度保守，而在 基因组中则略有更多的变异性。我们对 位点和 Tus 蛋白的序列分析表明，在所有研究的菌株中，叉状陷阱可能都是活跃的。此外，我们的分析表明， 染色体二聚体解析位点始终位于最内部 位点之间，即使最内部终止区域的位置发生了重排。我们的数据进一步支持了这样一种观点，即复制叉陷阱具有重要的生理作用，为其提供了进化优势。
