Dpb2p, a noncatalytic subunit of DNA polymerase epsilon, contributes to the fidelity of DNA replication in Saccharomyces cerevisiae.
Most replicases are multi-subunit complexes. DNA polymerase epsilon from Saccharomyces cerevisiae is composed of four subunits: Pol2p, Dpb2p, Dpb3p, and Dpb4p. Pol2p and Dpb2p are essential. To investigate a possible role for the Dpb2p subunit in maintaining the fidelity of DNA replication, we isolated temperature-sensitive mutants in the DPB2 gene. Several of the newly isolated dpb2 alleles are strong mutators, exhibiting mutation rates equivalent to pol2 mutants defective in the 3' --> 5' proofreading exonuclease (pol2-4) or to mutants defective in mismatch repair (msh6). The dpb2 pol2-4 and dpb2 msh6 double mutants show a synergistic increase in mutation rate, indicating that the mutations arising in the dpb2 mutants are due to DNA replication errors normally corrected by mismatch repair. The dpb2 mutations decrease the affinity of Dpb2p for the Pol2p subunit as measured by two-hybrid analysis, providing a possible mechanistic explanation for the loss of high-fidelity synthesis. Our results show that DNA polymerase subunits other than those housing the DNA polymerase and 3' --> 5' exonuclease are essential in controlling the level of spontaneous mutagenesis and genetic stability in yeast cells.
Jaszczur
Malgorzata
M
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
Flis
Krzysztof
K
Rudzka
Justyna
J
Kraszewska
Joanna
J
Budd
Martin E
ME
Polaczek
Piotr
P
Campbell
Judith L
JL
Jonczyk
Piotr
P
Fijalkowska
Iwona J
IJ
D019943:Amino Acid Substitution; D001483:Base Sequence; D003001:Cloning, Molecular; D004257:DNA Polymerase II / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
D017931:DNA Primers; D004268:DNA-Binding Proteins; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C529202:Dpb2 protein, S cerevisiae; D004257:DNA Polymerase II