Stephen Bell

Stephen Bell

Uncas and Helen Whitaker Professor of Biology; Director of Scientific Operations, Building 68; Investigator, Howard Hughes Medical Institute

Stephen Bell probes the cellular machinery that replicates and maintains animal cell chromosomes.





Elaine Aidonidis



Assistant Phone


  • PhD, 1990, University of California, Berkeley
  • BS, 1985, Integrated Science Program and Biochemistry, Molecular Biology and Cell Biology, Northwestern University

Research Summary

We focus on the events that occur at the starting points of chromosome duplication. These DNA sequences — called “origins of replication” — are found at multiple sites on each eukaryotic chromosome and direct the assembly of replisomes, which replicate the DNA on both sides of the origin. We study this assembly process to understand how chromosomes are replicated, and how these events are regulated during the cell cycle to ensure genome maintenance.


  • National Academy of Sciences, Member, 2017
  • National Academy of Sciences Award in Molecular Biology, 2009
  • Howard Hughes Medical Institute, HHMI Investigator, 2000

Key Publications

  1. Mechanism and timing of Mcm2-7 ring closure during DNA replication origin licensing. Ticau, S, Friedman, LJ, Champasa, K, Corrêa, IR Jr, Gelles, J, Bell, SP. 2017. Nat Struct Mol Biol 24, 309-315.
    doi: 10.1038/nsmb.3375PMID:28191892
  2. Single-molecule studies of origin licensing reveal mechanisms ensuring bidirectional helicase loading. Ticau, S, Friedman, LJ, Ivica, NA, Gelles, J, Bell, SP. 2015. Cell 161, 513-525.
    doi: 10.1016/j.cell.2015.03.012PMID:25892223
  3. Eukaryotic origin-dependent DNA replication in vitro reveals sequential action of DDK and S-CDK kinases. Heller, RC, Kang, S, Lam, WM, Chen, S, Chan, CS, Bell, SP. 2011. Cell 146, 80-91.
    doi: 10.1016/j.cell.2011.06.012PMID:21729781

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