Mutation of RNA polymerase sigma factor (RpoD) confers broad‑spectrum antimicrobial tolerance through global transcriptional reprogramming

ABSTRACT: The extensive use of antimicrobials has driven the emergence of multidrug‑resistant strains, posing a serious threat to public health. Less obvious is the problem of tolerance, a situation in which antimicrobial lethality is specifically inhibited even though the agents still block bacterial growth. Studies of tolerant mutants are leading to a better understanding of stress-mediated death as the gene products of the mutatons interfere with metabolic processes that generate reactive oxygen species. Here we continue to chacterize tolerance by enriching a mutant that acts through transcriptional reprogramming. A study of lysine‑potentiated β‑lactam-mediated killing revealed multidrug tolerance from a D445V substitution in RpoD, a sigma subunit of RNA polymerase. This substitution impairs the binding of the 2.4 region of RpoD to the -10 promoter element, thereby dampening RNA polymerase transcriptional activity. As a result, genes involved in ribosome biogenesis, purine and pyrimidine metabolism, ATP synthesis, and other core metabolic processes were down‑regulated, while ROS‑detoxifying genes (e.g., katEG and sodAB) were up‑regulated, thereby suppressing the accumulation of toxic metabolites such as ROS and enhancing antioxidant capacity when cells were treated with diverse antimicrobials. Both activities suppress and/or delay the lethal action of antimicrobials. Tolerance mediated by mutations in the PTS‑cAMP‑Crp pathway were suppressed by over-expression of rpoD, consistent with a transcription‑regulated pathway downstream from PTS‑cAMP‑Crp. These findings provide a conceptual foundation for understanding bacterial tolerance and developing new strategies to combat bacterial tolerance and resistance to antimicrobial therapy.

ORGANISM(S): Escherichia coli K-12

PROVIDER: GSE329627 | GEO | 2026/05/07

REPOSITORIES: GEO