Broad intraspecies killing activity in Pseudomonas syringae due to the combinatorial action of LPS-interacting bacteriocins

Bacteriocins are a diverse group of highly specific antimicrobials produced by bacteria, thought to mainly target and kill strains that are closely related to and which therefore potentially compete in the same niche space as producer cells. Single strains can produce more than one type of bacteriocin, with each usually having differing modes of action and receptors for binding, and with strain specificity for each independent bacteriocin due to the requirement for these molecules to bind to receptors in target cells prior to carrying out antibacterial functions. Here we show that Pseudomonas syringae pv. aptata DSM50252 (Ptt) displays broad intraspecific killing activity due to combinatorial and non-overlapping activities of phage derived bacteriocins (referred to as tailocins) as well as a prophage encoded lectin-like bacteriocin (aptatacin L1). These results highlight how single strains can maintain broad killing activity against a variety of potential competitors by targeting multiple conformations of a shared receptor, and provide additional evidence that tailocins and aptatacin L1 both utilize rhamnose moieties in the LPS as potential receptors for binding.