Tom Deegan

Mechanisms and regulation of chromosome replication.

Following undergraduate studies at the University of Oxford, Tom completed his PhD at CRUK Clare Hall laboratories under the supervision of John Diffley. Then, supported by a Sir Henry Wellcome postdoctoral fellowship from The Wellcome Trust, he did a postdoc with Karim Lab at the University of Dundee, where he worked on mechanisms of DNA replication termination and replisome disassembly. 

Since 2021, Tom has been a programme leader at the MRC Human Genetics Unit, where his lab continue to focus on molecular mechanisms of DNA replication.

portrait photo of Tom Deegan
Tom Deegan

Simone Pelliciari (postdoc), Emma Heron (postdoc), Tavi Olson (PhD student) and Maya Rowley (PhD student – joint with Marston lab)


Each time a cell divides, it must faithfully duplicate its chromosomes once and distribute them equally to the two daughter cells. This duplication is executed by macromolecular machines known as replisomes. To dissect chromosome replication at the molecular level, we reconstitute functional replisomes in vitro from purified yeast or human proteins. We integrate this biochemical system with structural biology and genetics to uncover fundamental mechanisms of DNA replication. Our current work focuses on the final stages of replication, the functions of accessory DNA helicases, and the assembly of the replisome’s helicase motor prior to replication initiation.


Two structural models of a protein

Olson, O, Pelliciari, S, Heron, ED, Deegan, TD (2024) A common mechanism for recruiting the Rrm3 and RTEL1 accessory helicases to the eukaryotic replisome. EMBO J. 43: 3846 – 3875.

Polo Rivera, C, Deegan, TD, Labib, KPM (2024) CMG helicase disassembly is essential and driven by two pathways in budding yeast. EMBO J. 43: 3818 – 3845.

Jenkyn-Bedford, M, Jones, M, Baris, Y, Labib, KPM, Cannone, G, Yeeles, JTP, Deegan, TD (2021) A conserved mechanism for regulating replisome disassembly in eukaryotes. Nature 600:743-747. 

Deegan, TD, Mukherjee, P, Fujisawa, R, Polo Rivera, C, Labib, KPM (2020) CMG helicase disassembly is controlled by replication fork DNA, replisome components and a ubiquitin threshold. eLife 2020;9:e60371. 

Deegan, TD, Baxter, J, Ortiz-Bazan, MA, Yeeles, JTP, Labib, KPM (2019) Pif1-Family Helicases Support Fork Convergence during DNA Replication Termination in Eukaryotes. Mol Cell. 74, 231-234.


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