The fifth essential DNA polymerase phi in Saccharomyces cerevisiae is localized to the nucleolus and plays an important role in synthesis of rRNA.
We report that POL5 encodes the fifth essential DNA polymerase in Saccharomyces cerevisiae. Pol5p was identified and purified from yeast cell extracts and is an aphidicolin-sensitive DNA polymerase that is stimulated by yeast proliferating cell nuclear antigen (PCNA). Thus, we named Pol5p DNA polymerase phi. Temperature-sensitive pol5-1-- -3 mutants did not arrest at G(2)/M at the restrictive temperature. Furthermore, the polymerase active-site mutant POL5dn gene complements the lethality of Delta pol5. These results suggest that the polymerase activity of Pol5p is not required for the in vivo function of Pol5p. rRNA synthesis was severely inhibited at the restrictive temperature in the temperature-sensitive pol5-3 mutant cells, suggesting that an essential function of Pol5p is rRNA synthesis. Pol5p is localized exclusively to the nucleolus and binds near or at the enhancer region of rRNA-encoding DNA repeating units.
Shimizu
Kikuo
K
Department of Biochemistry and Molecular Biology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
Kawasaki
Yasuo
Y
Hiraga
Shin-Ichiro
S
Tawaramoto
Maki
M
Nakashima
Naomi
N
Sugino
Akio
A
D000595:Amino Acid Sequence; D016590:Aphidicolin / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002455:Cell Division; D002466:Cell Nucleolus / Q000201:enzymology; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D012331:RNA, Fungal / Q000096:biosynthesis / Q000235:genetics; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D013696:Temperature
D004271:DNA, Fungal; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D016590:Aphidicolin; D004259:DNA-Directed DNA Polymerase