Pathogen-encoded Rum DNA polymerase drives rapid bacterial drug resistance

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Multidrug resistance (MDR) in pathogenic bacteria poses a significant global health threat.
• Horizontal gene transfer via mobile integrative conjugative elements (ICEs) is a primary mechanism for spreading antibiotic resistance genes.
• SXT/R391 ICEs frequently encode a hypermutagenic DNA polymerase, Rum pol, homologous to E. coli Pol V.

Purpose of the Study:

• To investigate the role of Rum pol in accelerating the development of multidrug resistance in E. coli.
• To determine the impact of Rum pol on antibiotic resistance acquisition under various stress conditions.
• To elucidate the regulatory involvement of RecA protein in Rum pol-mediated antibiotic resistance.

Main Methods:

• Experimental analysis of Rum pol activity in E. coli.
• Exposure of bacterial strains to antibiotic and non-antibiotic stressors (e.g., bleomycin, ciprofloxacin, UV radiation).
• Genetic manipulation of RecA protein, including specific amino acid substitutions (e.g., M197D), to assess regulatory effects.

Main Results:

• Rum pol significantly accelerates the acquisition of multidrug resistance (ciprofloxacin, rifampicin, ampicillin resistance) in E. coli.
• This acceleration occurs even under stringent transcriptional and post-transcriptional regulation.
• RecA protein is crucial for Rum pol's ability to enhance antibiotic resistance, with the RecA M197D mutation abolishing this effect.
• The contribution of Rum pol to resistance acquisition surpasses other cellular processes.

Conclusions:

• Rum pol is a major driver of de novo antibiotic resistance in bacteria harboring SXT/R391 ICEs.
• RecA acts as a master regulator controlling Rum pol-induced antibiotic resistance.
• Understanding Rum pol's function is critical for combating the spread of antibiotic resistance.