Life Without DNA Replication Origins

Speaker: Thorsten Allers, University of Nottingham, Queen's Medical Centre, UK
Host: Xu Peng (Section for Functional Genomics)

In 1963, François Jacob, Sydney Brenner and François Cuzin proposed the ‘replicon model’ to explain how DNA replication is regulated. They proposed that replication does not initiate at random points in the genome, rather it initiates at defined locations termed replication origins. Half a century later, this model has become a central tenet of biology.

We have recently shown that genome replication does not require defined origins. In the archaeon Haloferax volcanii, deletion of all origins results not in cell death but in significantly faster growth. We show that origin-less cells use homologous recombination to initiate DNA replication, and that this occurs randomly throughout the genome. These results lead us to question the need for replication origins and why they have evolved – we suggest that origins may have arisen as selfish genes.

Papers
Hawkins, M., Malla, S., Blythe, M., Nieduszynski, C.A. & T. Allers (2013): Accelerated growth in the absence of DNA replication origins. Nature 503, 544-7

Delmas, S., Duggin, I.G.L and Allers, T. (2013): DNA damage induces nucleoid compaction via the Mre11-Rad50 complex in the archaeon Haloferax volcanii. Molecular Microbiology. 87(1), 168-179

Yuan H, Liu X, Han Z, Allers T, Hou J and Liu J (2013): RecJ-like protein from Pyrococcus furiosus has 3'-5' exonuclease activity on RNA: implications for proofreading of 3'-mismatched RNA primers in DNA. Nucleic Acids Research, Volume 41, Issue 11, 5817-26.