title: Use of yeast transformation by oligonucleotides to study DNA lesion bypass in vivo.
abstract: We have studied mutagenic specificities of DNA lesions in vivo in yeast CYC1 oligonucleotide transformation assay. We introduced two lesions into oligonucleotides. One was a nucleoside analog, 3,4-dihydro-6H,8H-pyrimido[4,5-c][1,2]oxazin-7-one 2'-deoxyriboside (dP), which is highly mutagenic to bacteria. It is supposed to be a miscoding, but otherwise good template for DNA polymerases. The other lesion was the TT pyrimidine(6-4)pyrimidone photoproduct, one of the typical UV lesions, which blocks DNA replication. These oligonucleotides were used to transform yeast cyc1 mutants with ochre nonsense mutation to Cyc1+. As expected from its templating properties in vitro, the transforming activity of dP-containing oligonucleotides was similar to those of unmodified oligonucleotides. Results indicated that dP may direct incorporation of guanine and adenine at a ratio of 1:20 or more in vivo. An oligonucleotide containing the photoproduct showed the transforming activity of as low as 3-5% of that of the corresponding unmodified oligonucleotide. This bypass absolutely required REV1 gene. The sequence analysis of the transformants has shown that the lesion was read as TT and TC at a ratio of 3:7, indicating its high mutagenic potential.
authors: Gene Research Center, Okayama University, Tsushima, Okayama, Japan.
authors: Chie
authors: C
authors: Otsuka
authors: Keita
authors: K
authors: Kobayashi
authors: Naho
authors: N
authors: Kawaguchi
authors: Nozomu
authors: N
authors: Kunitomi
authors: Kei
authors: K
authors: Moriyama
authors: Yoshihiro
authors: Y
authors: Hata
authors: Shigenori
authors: S
authors: Iwai
authors: David
authors: D
authors: Loakes
authors: Vladimir N
authors: VN
authors: Noskov
authors: Youri
authors: Y
authors: Pavlov
authors: Kazuo
authors: K
authors: Negishi
mesh_terms: D001483:Base Sequence; D004249:DNA Damage; D017931:DNA Primers; D004271:DNA, Fungal / Q000235:genetics*; D009153:Mutagens / Q000494:pharmacology*; D009841:Oligonucleotides / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D017931:DNA Primers; D004271:DNA, Fungal; D009153:Mutagens; D009841:Oligonucleotides