Functional Differentiation and Cooperative Interaction Between Two Eukaryote-Like Archaeal Orc1/Cdc6 Proteins on the Replication Origin

Biochem Biophys Res Commun. 2007 Dec 28;364(4):945-51. doi: 10.1016/j.bbrc.2007.10.099. Epub 2007 Oct 25.


The DNA replication apparatus of archaea represents a core version of that in eukaryotes. Archaeal Orc1/Cdc6s can be an integral component in the replication machineries cooperatively regulating DNA replication. We investigated the DNA-binding activities of two eukaryote-like Orc1/Cdc6 proteins (SsoCdc6-1 and -2) and interactions between them on the different structural duplex DNA substrates derived from oriC1 of Sulfolobus solfataricus. The results showed that two Orc1/Cdc6 proteins stimulated mutual DNA-binding activities at lower concentrations and formed bigger SsoCdc6-1/SsoCdc6-2/DNA complex at higher concentrations. Furthermore, SsoCdc6-2 stimulated the DNA-binding activity of SsoMCM and demonstrated a high affinity to the 5-forked DNA. In contrast, SsoCdc6-1 inhibited the binding of SsoMCM and demonstrated better affinity to the sequence-specific blunt DNA substrate. Finally, we found that the two proteins physically interacted with each other and with SsoMCM. Thus, the two Orc1/Cdc6 proteins were functionally different, but they may keep the coordinated interaction on the replication origin.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / metabolism*
  • DNA Replication / physiology*
  • Origin Recognition Complex / metabolism*
  • Replication Origin / physiology*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Sulfolobus / metabolism*


  • CDC6 protein, S cerevisiae
  • Cell Cycle Proteins
  • Origin Recognition Complex
  • Saccharomyces cerevisiae Proteins