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Title: Structural and mechanistic insights into Mcm2-7 double-hexamer assembly and function

Eukaryotic cells license each DNA replication origin during G1 phase by assembling a prereplication complex that contains a Mcm2–7 (minichromosome maintenance proteins 2–7) double hexamer. During S phase, each Mcm2–7 hexamer forms the core of a replicative DNA helicase. However, the mechanisms of origin licensing and helicase activation are poorly understood. The helicase loaders ORC–Cdc6 function to recruit a single Cdt1–Mcm2–7 heptamer to replication origins prior to Cdt1 release and ORC–Cdc6–Mcm2–7 complex formation, but how the second Mcm2–7 hexamer is recruited to promote double-hexamer formation is not well understood. Here, structural evidence for intermediates consisting of an ORC–Cdc6–Mcm2–7 complex and an ORC–Cdc6–Mcm2–7–Mcm2–7 complex are reported, which together provide new insights into DNA licensing. Detailed structural analysis of the loaded Mcm2–7 double-hexamer complex demonstrates that the two hexamers are interlocked and misaligned along the DNA axis and lack ATP hydrolysis activity that is essential for DNA helicase activity. Moreover, we show that the head-to-head juxtaposition of the Mcm2–7 double hexamer generates a new protein interaction surface that creates a multisubunit-binding site for an S-phase protein kinase that is known to activate DNA replication. The data suggest how the double hexamer is assembled and how helicase activity is regulated during DNA licensing,more » with implications for cell cycle control of DNA replication and genome stability.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [3]
  1. Brookhaven National Laboratory (BNL), Upton, NY (United States)
  2. Brookhaven National Laboratory (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States)
  3. Imperial College Faculty of Medicine, London (United Kingdom). DNA Replication Group
  4. Imperial College Faculty of Medicine, London (United Kingdom). MRC Clinical Sciences Centre
  5. Stony Brook Univ., Stony Brook, NY (United States)
  6. Cold Spring Harbor Lab., NY (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0890-9369; 400412000
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Genes and Development
Additional Journal Information:
Journal Volume: 28; Journal Issue: 20; Journal ID: ISSN 0890-9369
Cold Springs Harbor Press
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
National Institutes of Health
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES origin recognition complex; DNA replication initiation; replicative helicase; prereplication complex; ; ELECTRON MICROSCOPY