Resistance to topoisomerase cleavage complex induced lethality in Escherichia coli via titration of transcription regulators PurR and FNR

• Published in: BMC microbiology Vol. 11; no. 1; p. 261
• Main Authors: Liu, I-Fen, Aedo, Sandra, Tse-Dinh, Yuk-Ching
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 12.12.2011; BioMed Central; BMC
• Subjects: Adenine; Antibiotics; Apoptosis; Bacteria; Binding sites; Cell death; Cell survival; Cloning; copy number; Derivatives; DNA; DNA topoisomerase; DNA topoisomerase I; DNA Topoisomerases, Type I - metabolism; Drug Resistance, Bacterial; E coli; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - enzymology; Escherichia coli - genetics; Escherichia coli Proteins; Experiments; Genetic aspects; genomics; Iron-Sulfur Proteins; Lethality; Libraries; Microbiology; Mutation; Norfloxacin; Norfloxacin - pharmacology; Nucleotides; Oxidative Stress; Oxygen; Physiological aspects; Plasmids; Proteins; purines; Quinolones; Quinolones - pharmacology; Repressor Proteins; Titration; Transcription; Transcription Factors - genetics; Yersinia - enzymology; Yersinia - genetics
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/1471-2180-11-261

Accumulation of gyrase cleavage complex in Escherichia coli from the action of quinolone antibiotics induces an oxidative damage cell death pathway. The oxidative cell death pathway has also been shown to be involved in the lethality following accumulation of cleavage complex formed by bacterial topoisomerase I with mutations that result in defective DNA religation. A high copy number plasmid clone spanning the upp-purMN region was isolated from screening of an E. coli genomic library and analyzed for conferring increased survival rates following accumulation of mutant topoisomerase I proteins as well as treatment with the gyrase inhibitor norfloxacin. Analysis of the intergenic region upstream of purM demonstrated a novel mechanism of resistance to the covalent protein-DNA cleavage complex through titration of the cellular transcription regulators FNR and PurR responsible for oxygen sensing and repression of purine nucleotide synthesis respectively. Addition of adenine to defined growth medium had similar protective effect for survival following accumulation of topoisomerase cleavage complex, suggesting that increase in purine level can protect against cell death. Perturbation of the global regulator FNR and PurR functions as well as increase in purine nucleotide availability could affect the oxidative damage cell death pathway initiated by topoisomerase cleavage complex.