Genomic Correlates of Tailocin Sensitivity inPseudomonas syringae

Abstract

AbstractPhage derived bacteriocins, also referred to as tailocins, are structures encoded by bacterial genomes and deployed into the extracellular environment to target and kill sensitive cells. Tailocins display great potential as agricultural antimicrobials due to their durability, efficiency, and specificity of killing with prophylactic application of these molecules having been shown to prevent infection by multiple phytopathogens. Although previous reports have strongly suggested that tailocins ofPseudomonas syringaebind sugar moieties in the lipopolysaccharide of target cells, the molecular mechanisms and binding interactions that enable tailocins fromP. syringaeto kill sensitive targets remain unclear. We therefore carried out a genome-wide association study investigating tailocin sensitivity across a diverse set ofP. syringaegenomes. Our results demonstrate that genes strongly correlated with tailocin sensitivity are localized to one contiguous region on theP. syringaechromosome encoding LPS structures similar to the Common Polysaccharide Antigen ofP. aeruginosa. We further find that enzymes involved in the biosynthesis and transport of D-rhamnose and L-rhamnose are associated with tailocin sensitivity classes A and B, respectively, with large-scale recombination of the O-antigen biosynthesis region likely underlying rapid and fundamental changes in LPS structure between strains. Lastly, we identify therfbDgene as an additional genomic indicator to predict tailocin sensitivity and use this information to test tailocin interactions with previously unscreened strains from across phylogroups.