Pathogens such as uropathogenic Escherichia coli (UPEC), must adapt their metabolism according to the nutrients available inside the host in order to survive and cause infection, such as those of the bladder, kidney and bloodstream. This metabolic capacity and flexibility of UPEC has been recognised to be important for pathogenesis in the urinary tract.
Here, we utilized transposon mutagenesis in combination with an improved protocol for transposon-directed insertion-site sequencing (TraDIS), which maps transposon insertions in a pooled collection of random mutants, to define genes required for growth of UPEC in glycerol-supplemented minimal-media when compared to rich media. We identified 71 mutants with a reduced capacity to survive, the majority of which encode gluconeogenic and amino acid catabolism proteins. Further investigations of a subset of mutants confirmed a reproducible reduced capacity for survival. Additionally, we identified several uncharacterised and UPEC-specific proteins that have great potential to underlie the metabolic capacities seen in UPEC strains. The deletion effect of one of these genes, neuC, implicated in sialic acid biosynthesis, on the ability of UPEC to infect and colonise human bladder epithelial cells using a gentamicin protection assay was examined. This revealed that loss of neuC resulted in a reduction of UPEC colony forming units (CFU) 24 hrs post-infection when compared to wild-type. This highlights the important role metabolic genes play in adapting to conditions experienced by UPEC during infection.