The Rtc RNA repair system is linked to virulence in Escherichia coli

Abstract

Antibiotic resistance is one of the biggest public health challenges of the 21st century. The Rtc RNA repair system is present in many pathogenic bacterial species, including the model organism and putative pathogen Escherichia coli, and may play a role in antibiotic resistance. Here we explore its physiological role during infection. Pathogenicity assays are being performed using the infection model Galleria mellonella, to study the phenotypes and survival rates following larvae infection with E. coli K12 and variants lacking rtc genes. Larvae infected with wild-type bacteria survive for up to 10 days as opposed to those lacking any of the rtc genes, which survive for up to 14 days on average. Complementation of the rtc gene deletions with wild-type Rtc proteins, but not functionally catalytic mutants, reverses the infection phenotype to that of wild-type. Similarly, viable larvae infected with wild-type or complemented bacteria score much lower in a health index scoring system than those infected with strains either lacking any of rtc genes or expressing catalytically inactive Rtc proteins. To further explore the importance of Rtc in infection, bacterial burden assays will be conducted to measure the bacterial load. The results so far suggest that bacteria with a fully functional Rtc system are more aggressive in the G. mellonellainfection model. This outcome supports the notion that the Rtc RNA repair system is involved in bacterial virulence and opens the window for further research to understand the ways in which Rtc may contribute to resistance, with potential for broader health benefit.