Archaeal eukaryote-like Orc1/Cdc6 initiators physically interact with DNA polymerase B1 and regulate its functions

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Archaeal DNA replication shares core similarities with eukaryotes.
• Key proteins coordinating origin selection and DNA polymerase function in archaea remain under investigation.
• Eukaryotic homologs of these proteins are also areas of ongoing research.

Purpose of the Study:

• To investigate the interaction between Orc1/Cdc6 and DNA polymerase in the archaeon Sulfolobus solfataricus.
• To characterize the functional consequences of this interaction on DNA polymerase activity and binding.
• To explore the potential roles of Orc1/Cdc6 in archaeal DNA replication regulation.

Main Methods:

• Co-immunoprecipitation to confirm physical interaction between SsoCdc6 and SsoPolB1.
• Enzyme activity assays to assess polymerase and nuclease functions.
• DNA-binding assays to evaluate SsoPolB1's affinity for DNA.
• Analysis of a nuclease-deficient mutant (SsoPolB1c467).

Main Results:

• SsoCdc6 proteins physically interact with SsoPolB1.
• SsoCdc6 stimulates SsoPolB1's DNA-binding ability.
• SsoCdc6 differentially regulates SsoPolB1's polymerase and nuclease activities.
• A nuclease-deficient SsoPolB1 mutant retains interaction with SsoCdc6 and shows stimulated polymerase activity.

Conclusions:

• A direct functional linkage exists between initiator proteins (Orc1/Cdc6) and DNA polymerase in archaea.
• Archaeal Orc1/Cdc6 proteins likely play crucial roles in coordinating DNA replication origin selection.
• These findings suggest a role for Orc1/Cdc6 in archaeal cell-cycle control of replication.