Atypical DNA replication in the absence of origins in archaeon Haloferax volcanii

人们普遍认为DNA复制是从基因组内的特定区域开始的，这被称为“复制的起源”。虽然起源以前被认为是生存所必需的，但在古菌Haloferax volcanii中，删除所有复制的染色体起源没有任何不良影响，无起源细胞的生长速度比野生型菌株快7.5% （Hawkins et al., 2013, Nature, doi:10.1038/nature12650）。复制的起始通常被很好地理解：起源识别蛋白质在起源处将DNA重塑为更开放的结构，允许复制成分的装载，这将形成一个功能性的“复制体”，将复制DNA。对于没有起源的DNA是如何复制的，我们知之甚少；起源和起源识别蛋白在H. volcanii中是不必需的，因此必须发生另一种复制起始模式。该项目旨在评估在缺乏复制起源的细胞中如何改变复制的分子机制。将分析复制所需的组件，并评估依赖于起源和独立于起源的复制之间的差异。

DNA replication is widely accepted to initiate at specific areas within the genome, known as 'origins of replication'. Whilst origins were previously thought to be essential for survival, deletion of all chromosomal origins of replication in archaeon Haloferax volcanii has no ill effect, with originless cells growing 7.5% faster than the wild type strain (Hawkins et al., 2013, Nature, doi:10.1038/nature12650). Initiation of replication is generally well understood: origin recognition proteins remodel DNA at the origin to a more open structure, allowing loading of replication components, which will form a functional 'replisome' that will replicate the DNA. Little is known about how DNA is replicated without origins; origins and origin recognition proteins are non-essential in H. volcanii, and thus an alternate mode of replication initiation must be occurring. This project aims to assess how the molecular mechanisms of replication are altered in cells lacking origins of replication. The components required for replication will be analysed and differences between origin-dependent and origin-independent replication will be assessed.