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

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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.