Structure and Function Studies of Replication Initiation Factors

  • Jingchuan Sun
  • Zuanning Yuan
  • Bruce StillmanEmail author
  • Christian SpeckEmail author
  • Huilin LiEmail author


We have used negative stain EM and cryo-EM to visualize step by step the replication initiation events in S. cerevisiae, as the process is driven forward by the interplay of a dozen or so macromolecular initiation factors, leading to the establishment of pre-replication complexes (pre-RC) at each origin of DNA replication. This work took advantage of our ability to reconstitute the Mcm2-7 loading reaction with purified proteins. We determined the architecture of several previously known replication initiation complexes such as ORC, ORC-Cdc6 on DNA, and the Mcm2-7 double hexamer. We also captured by EM reaction intermediates such as the ORC-Cdc6-Cdt1-Mcm2-7 (OCCM) and the ORC-Cdc6-Mcm2-7-Mcm2-7 (OCMM) that had evaded previous biochemical identification. In this chapter, we describe what we have learnt about the structure and interaction with origin DNA of the replication initiators. We further discuss what may be expected in the coming years as cryo-EM is becoming a near-atomic resolution structural tool, thanks to the recent advent of the direct electron detector.


Origin replication complex (ORC) Pre-replication complex (pre-RC) Mcm2-7 Replicative helicase Replication initiator cryo-EM Structural biology 



Many people in the labs of Huilin Li, Christian Speck, and Bruce Stillman have helped in this work. The work was supported by National Institutes of Health grant numbers GM45436 (to B.S.) and GM74985 (to H.L.) and the United Kingdom Biotechnology and Biological Sciences Research Council (to C.S.).


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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Biosciences DepartmentBrookhaven National LaboratoryUptonUSA
  2. 2.Department of Biochemistry and Cell BiologyStony Brook UniversityStony BrookUSA
  3. 3.Cold Spring Harbor LaboratoryCold Spring HarborUSA
  4. 4.DNA Replication Group, Imperial College London, Faculty of MedicineInstitute of Clinical SciencesLondonUK

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