Transcriptional Mutagenesis Induced by Uracil and 8-Oxoguanine in Escherichia coli

• Published in: Molecular cell Vol. 12; no. 4; pp. 959 - 970
• Main Authors: Brégeon, Damien, Doddridge, Zara A, You, Ho Jin, Weiss, Bernard, Doetsch, Paul W
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2003; Cell Press
• Subjects: Base Sequence - drug effects; Base Sequence - genetics; DNA Damage - genetics; DNA Repair - genetics; DNA-Directed RNA Polymerases - metabolism; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli Proteins - biosynthesis; Escherichia coli Proteins - genetics; Gene Expression Regulation, Bacterial - drug effects; Gene Expression Regulation, Bacterial - genetics; Guanine - analogs & derivatives; Guanine - pharmacology; Life Sciences; Mutagenesis - drug effects; Mutagenesis - genetics; Phenotype; Transcription, Genetic - drug effects; Transcription, Genetic - genetics; Uracil - metabolism; Uracil - pharmacology
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/S1097-2765(03)00360-5

Cells exposed to DNA damaging agents in their natural environment do not undergo continuous cycles of replication but are more frequently engaged in gene transcription. Luciferase gene expression analysis with DNA templates containing uracil or 8-oxoguanine, placed at a defined position, indicated that in nondividing Escherichia coli cells, efficient mutagenic lesion bypass does occur in vivo during transcription. Sequence analyses of the transcript population revealed that RNA polymerase inserts adenine opposite to uracil, and adenine or cytosine opposite to 8-oxoguanine. Surprisingly, deletions were also detected for 8-oxoguanine-containing templates, indicating RNA polymerase slippage over this lesion. Genetic analyses showed that, in E. coli, 8-oxoguanine is subject to transcription-coupled repair. Consequently, DNA damages alter transcription fidelity in vivo, which may lead to the production of mutant proteins that have the potential to change the phenotype of nondividing cells.