Genomic and functional characterization of the L‑sorbose phosphotransferase system in high-risk Escherichia coli...

Certain Escherichia coli strains belong to international high-risk clonal lineages exhibiting a combination of multidrug resistance, enhanced fitness, and increased virulence, posing major public health challenges. Investigation of characteristics beyond antibiotic resistance genes and classical virulence factors is crucial to gain understanding of common traits among these pathogens. Analysis of 22,267 publicly available E. coli genomes from five pathogenic and one commensal sequence type (ST) revealed the L-sorbose phosphotransferase system (PTS ) as a pathogen-enriched marker. Although previously investigated for evolutionary insights, this system has not been functionally assessed within high-risk clonal lineages, as performed in the present study. Our multi-omics results demonstrate that the L-sorbose PTS is induced in pathogenic strains of ST131 and ST648 in the presence of L-sorbose, conferring a competitive advantage compared to a commensal ST10 strain. Transcriptomic analysis revealed co-regulated pathways involving metabolism, flagellar motility, and capsular polysaccharide production, indicating roles in niche adaptation. Despite some strain-specific variations, functional assays with knock-out/knock-in mutants and Galleria mellonella infection models confirmed the operon's impact on competition and fitness.

This study highlights the value of combining large-scale genomic analyses with functional validation for identifying and analyzing the L‑sorbose phosphotransferase system in different E. coli high-risk clones. This knowledge may be applied in future studies to address the need for identifying alternative, pathogen-specific targets.