Inactivation of UmuC Protein Significantly Reduces Resistance to Ciprofloxacin and SOS Mutagenesis in Escherichia coli Mutants Harboring Intact umuD Gene

Background: Ciprofloxacin induces SOS response and mutagenesis by activation of UmuD’2C (DNA polymerase V) DinB IV) in Escherichia coli, leading to antibiotic resistance during therapy. Inactivation DNA V can result the inhibition E. coli. Objectives: The aim this research was investigate effect UmuC inactivation on ciprofloxacin coli mutants. Methods: Ciprofloxacin-resistant mutants were produced a umuC- genetic background presence increasing concentrations ciprofloxacin. minimum inhibitory concentration umuC-mutants measured broth dilution method. Alterations rifampin resistance-determing region rpoB gene assessed PCR amplification sequencing. expression genes quantitative real-time assay. Results: Results showed that despite induction (overexpression recA, dinB, umuD genes) following exposure umuC mutants, significantly decreased. However, rifampicin-resistant clones emerged background. One these mutations rifampicin resistance-determining (cluster II). low mutation frequency might be associated with overexpression gene, which could somehow limit activity DinB, location type β subunit RNA polymerase. Conclusions: In conclusion, for efficiency against Gram-negative bacteria, use an inhibitor umuC, along ciprofloxacin, would helpful.