Antibiotic-induced DNA damage results in a controlled loss of pH homeostasis and genome instability

• Published in: Scientific reports Vol. 10; no. 1; p. 19422
• Main Authors: Booth, James Alexander, Špírek, Mário, Lobie, Tekle Airgecho, Skarstad, Kirsten, Krejci, Lumir, Bjørås, Magnar
• Format: Journal Article
• Language: English; Norwegian
• Published: England Nature Publishing Group 10.11.2020; Nature Publishing Group UK
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotic resistance; Antibiotics; Deoxyribonucleic acid; DNA; DNA damage; DNA Damage - drug effects; DNA Damage - genetics; DNA Damage - radiation effects; Drug resistance; Electrophoretic Mobility Shift Assay; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli - radiation effects; Filamentation; Flow Cytometry; Genomes; Genomic instability; Genomic Instability - drug effects; Genomic Instability - genetics; Genomic Instability - radiation effects; Homeostasis; Hydrogen-Ion Concentration; Macrophages; Microbial Viability - drug effects; Microbial Viability - radiation effects; Mutagenesis; Nalidixic acid; Nalidixic Acid - pharmacology; pH effects; Propidium - pharmacology; RecA protein; Resistant mutant; Rifampin - pharmacology; Transcription; Ultraviolet Rays
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-76426-2

Extracellular pH has been assumed to play little if any role in how bacteria respond to antibiotics and antibiotic resistance development. Here, we show that the intracellular pH of Escherichia coli equilibrates to the environmental pH following treatment with the DNA damaging antibiotic nalidixic acid. We demonstrate that this allows the environmental pH to influence the transcription of various DNA damage response genes and physiological processes such as filamentation. Using purified RecA and a known pH-sensitive mutant variant RecA K250R we show how pH can affect the biochemical activity of a protein central to control of the bacterial DNA damage response system. Finally, two different mutagenesis assays indicate that environmental pH affects antibiotic resistance development. Specifically, at environmental pH's greater than six we find that mutagenesis plays a significant role in producing antibiotic resistant mutants. At pH's less than or equal to 6 the genome appears more stable but extensive filamentation is observed, a phenomenon that has previously been linked to increased survival in the presence of macrophages.