3' to 5' exonuclease activity located in the DNA polymerase delta subunit of Saccharomyces cerevisiae is required for accurate replication

• Published in: The EMBO journal 1991-08, Vol.10 (8), p.2165-2170
• Main Authors: Simon, M, Giot, L, Faye, G
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Biological and medical sciences; DNA Polymerase III; DNA Replication; DNA, Fungal - biosynthesis; DNA-directed DNA polymerase; DNA-Directed DNA Polymerase - genetics; DNA-Directed DNA Polymerase - metabolism; exonuclease proofreading; Exonucleases - metabolism; Fundamental and applied biological sciences. Psychology; Genes, Fungal; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Plasmids; Replication; Restriction Mapping; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1991.tb07751.x

In Saccharomyces cerevisiae, DNA polymerase delta (POLIII), the product of the CDC2 (POL3) gene, possesses, in its N-terminal half, the well conserved 3-domain 3' to 5' exonuclease site. Strains selectively mutagenized in this site display a mutator phenotype detected as a drastically increased spontaneous forward mutation rate to canavanine resistance or as an elevated reversion rate to lysine prototrophy. Assays on a partially purified extract of the mutant giving the largest mutator effect indicate that the 3' to 5' exonuclease activity is reduced below the detection limit whereas the DNA polymerizing activity has wild-type level. Therefore, our results provide experimental support for the hypothesis that the exonucleolytic proofreading activity associated with DNA polymerase delta resides on the DNA polymerase delta subunit and enhances the fidelity of DNA replication in east.