A novel single-stranded DNA-binding protein from the Novikoff hepatoma which stimulates DNA polymerase beta. Purification and general characterization.
We have isolated and purified to homogeneity a novel single-stranded DNA-binding protein from the Novikoff hepatoma. This protein is distinguished from other eukaryotic DNA-binding proteins by binding weakly, but cooperatively, to single-stranded DNA, by its ability to partially destabilize a double helix at 37 degrees C, and by its ability to stimulate DNA polymerase beta. The protein exists as a globular monomer of Mr = 48,000 and is capable of binding 45-49 nucleotides. It does not form a complex with the polymerase, but binds the DNA template, allowing an increased rate and extent of DNA synthesis. The enhancement of synthesis is greatest with larger gap-sized templates and with low polymerase concentrations. The mechanism of stimulation is thought to be due largely to placing the template strand into a conformation that facilitates rapid polymerization rather than strand displacement in advance of the polymerase. This protein has been named SSB-48.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004256:DNA Polymerase I / Q000378:metabolism*; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D006358:Hot Temperature; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D051381:Rats
D000596:Amino Acids; D002352:Carrier Proteins; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase