title: Removal of 8-oxo-GTP by MutT hydrolase is not a major contributor to transcriptional fidelity.
abstract: Living in an oxygen-rich environment is dangerous for a cell. Reactive oxygen species can damage DNA, RNA, protein and lipids. The MutT protein in Escherichia coli removes 8-oxo-deoxyguanosine triphosphate (8-oxo-dGTP) and 8-oxo-guanosine triphosphate (8-oxo-GTP) from the nucleotide pools precluding incorporation into DNA and RNA. While 8-oxo-dGTP incorporation into DNA is mutagenic, it is not clear if 8-oxo-GTP incorporation into RNA can have phenotypic consequences for the cell. We use a bistable epigenetic switch sensitive to transcription errors in the Escherichia coli lacI transcript to monitor transient RNA errors. We do not observe any increase in epigenetic switching in mutT cells. We revisit the original observation of partial phenotypic suppression of a lacZamber allele in a mutT background that was attributed to RNA errors. We find that Lac+ revertants can completely account for the increase in β-galactosidase levels in mutT lacZamber cultures, without invoking participation of transient transcription errors. Moreover, we observe a fluctuation type of distribution of β-galactosidase appearance in a growing culture, consistent with Lac+ DNA revertant events. We conclude that the absence of MutT produces a DNA mutator but does not equally create an RNA mutator.
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Alasdair J E
authors.initials: AJ
authors.lastname: Gordon
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Dominik
authors.initials: D
authors.lastname: Satory
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, 77030, USA.
authors.forename: Mengyu
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Halliday
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, 77030, USA Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Ido
authors.initials: I
authors.lastname: Golding
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA herman@bcm.edu.
authors.forename: Christophe
authors.initials: C
authors.lastname: Herman
mesh_terms: D003848:Deoxyguanine Nucleotides / Q000378:metabolism*; D044127:Epigenesis, Genetic; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D053263:Gene Regulatory Networks; D007763:Lac Operon; D056968:Lac Repressors / Q000235:genetics; D009154:Mutation; D011755:Pyrophosphatases / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D003848:Deoxyguanine Nucleotides; D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; C078206:8-oxodeoxyguanosine triphosphate; D001616:beta-Galactosidase; D011755:Pyrophosphatases; C052211:mutT protein, E coli