Topoisomerase I function during Escherichia coli response to antibiotics and stress enhances cell killing from stabilization of its cleavage complex

• Published in: Journal of antimicrobial chemotherapy Vol. 66; no. 7; pp. 1518 - 1524
• Main Authors: Liu, I-Fen, Sutherland, Jeanette H., Cheng, Bokun, Tse-Dinh, Yuk-Ching
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.07.2011; Oxford Publishing Limited (England)
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics; Antibiotics. Antiinfectious agents. Antiparasitic agents; Apoptosis; Artificial Gene Fusion; Biological and medical sciences; Blotting, Western; DNA Topoisomerases, Type I - deficiency; DNA Topoisomerases, Type I - metabolism; E coli; Enzymes; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - enzymology; Escherichia coli Proteins - biosynthesis; Escherichia coli Proteins - genetics; Gene Deletion; Genes, Reporter; Luciferases - genetics; Luciferases - metabolism; Medical sciences; Microbial Viability - drug effects; Mitomycin - pharmacology; Nitrites - pharmacology; Original Research; Pharmacology. Drug treatments; Rec A Recombinases - biosynthesis; Rec A Recombinases - genetics; Stress response; Trimethoprim - pharmacology; drug targets; killing; anti-infective development; stress response; gene expression; Stability; Enzyme; Stabilization; Escherichia coli; DNA topoisomerase; Gene expression; In vitro; Stress; Antibiotic; Isomerases; Targeted drug; Development; Bacteria; Cleavage; Antiinfectious; Antibacterial agent; Cell; Physicochemical properties; Enterobacteriaceae
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkr150

Objectives To explore the role of topoisomerase I in gene activation and increased RecA levels during the bacterial SOS response, as well as the effect of antibiotic treatment and stress challenge on cell killing initiated by trapped topoisomerase I cleavage complex. Methods A mutant Escherichia coli strain with a ΔtopA mutation was used to investigate the role of topoisomerase I function in the SOS response to trimethoprim and mitomycin C. Induction of the recA and dinD1 promoters was measured using luciferase reporters of these promoters fused to luxCDABE. An increase in the RecA level following trimethoprim treatment was quantified directly by western blotting. The effect of stress challenge from trimethoprim and acidified nitrite treatments on cell killing by topoisomerase I cleavage complex accumulation was measured by the decrease in viability following induction of recombinant mutant topoisomerase I that forms a stabilized cleavage complex. Results Topoisomerase I function was found to be required for efficient transcriptional activation of the recA and dinD1 promoters during the E. coli SOS response to trimethoprim and mitomycin C. The role of topoisomerase I in the SOS response was confirmed with quantitative western blot analysis of RecA following trimethoprim treatment. The bactericidal effect from topoisomerase I cleavage complex accumulation was shown to be enhanced by stress challenge from trimethoprim and acidified nitrite. Conclusions Bacterial topoisomerase I function is actively involved in the SOS response to antibiotics and stress challenge. Cell killing initiated by the topoisomerase I cleavage complex would be enhanced by antibiotics and the host response. These findings provide further support for bacterial topoisomerase I as a therapeutic target.