Functional interactions of an archaeal sliding clamp with mammalian clamp loader and DNA polymerase delta.
BACKGROUND
By the total genome sequencing of several archaeal organisms, it has been confirmed that many archaeal proteins related to genetic information systems, including DNA replication, transcription and translation, have similar sequences to those of eukaryotes. In eukaryotic DNA replication, proliferating cell nuclear antigen (PCNA) works in clamping DNA polymerases on the DNA template and accomplishes a processive DNA synthesis. Archaea encode PCNA homologues in their genomes and Pyrococcus furiosus PCNA (PfuPCNA) stimulates the DNA synthesizing activities of the DNA polymerases, Pol I and Pol II, in this organism.


RESULTS
We have demonstrated that PfuPCNA interacts functionally with calf thymus DNA polymerase delta (Pol delta) and stimulates its activity. Moreover, human replication factor C (RFC) enhances the PfuPCNA-dependent DNA synthesis activity of Pol delta, indicating that human RFC works as the clamp loader for PfuPCNA. These results showed that the three-dimensional structures of archaral PCNA and RFC are actually similar enough to their eukaryotic counterparts to allow a molecular substitution between the two biological domains, albeit at a lower efficiency.


CONCLUSIONS
We found that the archaeal molecule interacts functionally with the eukaryotic members in the DNA replication process. This finding supports the idea that studies on the DNA replication mechanism of archaeal organisms will provide many important clues for understanding of the intricate molecular recognition that is inherent to the DNA replication machinery in Eukarya.
Ishino
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Department of Molecular Biology, Biomolecular Engineering Research Institute, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan. ishino@beri.co.jp
Tsurimoto
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Ishino
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Cann
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IK
D000818:Animals; D002417:Cattle; D003001:Cloning, Molecular; D004258:DNA Polymerase III / Q000378:metabolism*; D004261:DNA Replication; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004926:Escherichia coli; D019766:Genes, Archaeal; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020027:Pyrococcus furiosus / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D051818:Replication Protein C; D013045:Species Specificity; D013950:Thymus Gland / Q000201:enzymology
D019641:DNA, Archaeal; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D018809:Proliferating Cell Nuclear Antigen; D011994:Recombinant Proteins; C072146:Pfu DNA polymerase; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D051818:Replication Protein C