ATPase-dependent cooperative binding of ORC and Cdc6 to origin DNA

Nat Struct Mol Biol. 2005 Nov;12(11):965-71. doi: 10.1038/nsmb1002.


Binding of Cdc6 to the origin recognition complex (ORC) is a key step in the assembly of a pre-replication complex (pre-RC) at origins of DNA replication. ORC recognizes specific origin DNA sequences in an ATP-dependent manner. Here we demonstrate cooperative binding of Saccharomyces cerevisiae Cdc6 to ORC on DNA in an ATP-dependent manner, which induces a change in the pattern of origin binding that requires the Orc1 ATPase. The reaction is blocked by specific origin mutations that do not interfere with the interaction between ORC and DNA. Single-particle reconstruction of electron microscopic images shows that the ORC-Cdc6 complex forms a ring-shaped structure with dimensions similar to those of the ring-shaped MCM helicase. The ORC-Cdc6 structure is predicted to contain six AAA+ subunits, analogous to other ATP-dependent protein machines. We suggest that Cdc6 and origin DNA activate a molecular switch in ORC that contributes to pre-RC assembly.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Cell Cycle Proteins / metabolism*
  • Cell Cycle Proteins / ultrastructure
  • DNA / genetics
  • DNA / metabolism*
  • DNA Footprinting
  • DNA Primers
  • Electrophoretic Mobility Shift Assay
  • Microscopy, Electron
  • Models, Molecular*
  • Molecular Sequence Data
  • Multiprotein Complexes / chemistry*
  • Multiprotein Complexes / ultrastructure
  • Mutation / genetics
  • Origin Recognition Complex / metabolism*
  • Origin Recognition Complex / ultrastructure
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / ultrastructure
  • Structure-Activity Relationship


  • CDC6 protein, S cerevisiae
  • Cell Cycle Proteins
  • DNA Primers
  • Multiprotein Complexes
  • ORC1 protein, S cerevisiae
  • Origin Recognition Complex
  • Saccharomyces cerevisiae Proteins
  • DNA