Flagellin O-linked glycans are required for the interactions between Campylobacter jejuni and Acanthamoebae castellanii

Abstract

The predation and engulfment of bacteria by Acanthamoebae facilitates intimate interactions between host and prey. This process plays an important and underestimated role in the physiology, ecology and evolution of pathogenic bacteria. Acanthamoebae species can be reservoirs for many important human pathogens including Campylobacter jejuni. C. jejuni is the leading cause of bacterial foodborne enteritis worldwide, despite being a microaerophile that is incapable of withstanding atmospheric levels of oxygen long-term. The persistence and transmission of this major pathogen in the natural environment outside its avian and mammalian hosts is not fully understood. Recent evidence has provided insight into the relationship of C. jejuni and Acanthamoebae spp. where Acanthamoebae are a transient host for this pathogen. Mutations to the flagella components were shown to affect C. jejuni–A. castellanii interactions. Here, we show that the motility function of flagella is not a prerequisite for C. jejuni–A. castellanii interactions and that specific O-linked glycan modifications of the C. jejuni major flagellin, FlaA, are important for the recognition, interaction and phagocytosis by A. castellanii. Substitution of the O-linked glycosylated serine 415 and threonine 477 with alanine within FlaA abolished C. jejuni interactions with A. castellanii and these mutants were indistinguishable from a ΔflaA mutant. By contrast, mutation to serine 405 did not affect C. jejuni 11168H and A. castellanii interactions. Given the abundance of flagella glycosylation among clinically important pathogens, our observations may have a wider implication for understanding host–pathogen interactions.

Long-term Culturing ofPseudomonas aeruginosain Static, Minimal Nutrient Medium Results in Increased Pyocyanin Production, Reduced Biofilm Production, and Loss of Motility

“…castellanii to initiate phagocytosis [47,48]. Thus, if there are fewer/less flagella expressed in the evolved isolates, there would be less predation by A. castellanii resulting in starvation of the amoebae predator when in co-culture with the evolved lineages.…”