A 2026 Crick PhD project with John Diffley.

Project background and description

DNA replication is one of the most fundamental processes in cell biology. In eukaryotes, replication initiates from large numbers of sites, known as origins, distributed along multiple chromosomes [1]. Initiation from these sites must be carefully regulated to ensure that the entire genome is precisely duplicated in each cell cycle, that this process is coordinated with chromosome segregation and that the commitment to replication is coordinated with cell growth.

Much of this regulation occurs at the level of initiation.  Initiation of replication in eukaryotes is a two-step process. In the first step, the MCM replicative helicase is loaded as a head-to-head double hexamer around double stranded DNA.  In the second step, the helicase is activated, which involves splitting the double hexamer, melting the DNA within the MCM central channel, opening the MCM ring, extruding the lagging strand template and reclosing the ring around the single-strand leading strand template; all of this is coordinated with recruitment of two essential accessory factors, Cdc45 and GINS. To accomplish this a plethora of MCM loading and activation factors are involved.  Despite its centrality in biology and the fact that the accessory factors are largely conserved across Eukarya, our recent work has shown that the mechanism of MCM loading and activation differs significantly between yeast and humans [2-4].  In this project you will continue to explore these differences using biochemistry and genetics, exploiting our fully reconstituted initiation reaction [5] and the power of yeast genetics with an aim to gain insight into some of the principles governing evolution of this process.

Candidate background

I believe deep understanding of biological processes requires both genetics and biochemistry. I am, therefore, especially interested in candidates with a strong background in one and a willingness to learn the other.

References