Determinants that govern the recognition and uptake ofEscherichia coliO157 : H7 byAcanthamoeba castellanii

Abstract

Predation by phagocytic predators is a major source of bacterial mortality. The first steps in protozoan predation are recognition and consumption of their bacterial prey. However, the precise mechanisms governing prey recognition and phagocytosis by protists, and the identities of the molecular and cellular factors involved in these processes are, as yet, ill-characterized. Here, we show that that the ability of the phagocytic bacterivorous amoebae, Acanthamoeba castellanii, to recognize and internalize Escherichia coli, a bacterial prey, varies with LPS structure and composition. The presence of an O-antigen carbohydrate is not required for uptake of E. coli by A. castellanii. However, O1-antigen types, not O157 O-antigen types, inhibit recognition and uptake of bacteria by amoeba. This finding implies that O-antigen may function as an antipredator defence molecule. Recognition and uptake of E. coli by A. castellanii is mediated by the interaction of mannose-binding protein located on amoebae's surface with LPS carbohydrate. Phagocytic mammalian cells also use mannose-binding lectins to recognize and/or mediate phagocytosis of E. coli. Nonetheless, A. castellanii's mannose binding protein apparently displays no sequence similarity with any known metazoan mannose binding protein. Hence, the similarity in bacterial recognition mechanisms of amoebae and mammalian phagocytes may be a result of convergent evolution.

Unravelling the interactions of the environmental hostAcanthamoeba castellaniiwith fungi through the recognition by mannose‐binding proteins

“…MBPs of Ac could also recognise Arcobacter butzleri (Allen & Dawidowicz, ) and specifically mediate the uptake of Legionella pneumophila (Declerck et al, ). However, the Ac MBPs display no sequence similarity with known mammalian MBPs suggesting that amoebae and mammalian phagocytes had a convergent evolution (Arnold, Spacht, & Koudelka, ).…”

Adhesion of Campylobacter jejuni Is Increased in Association with Foodborne Bacteria

“…Also, the species composition of biofilms in vivo can change by up to 40% every day with multispecies biofilms [18], where the levels of C. jejuni have been shown to be enhanced after 24 h when incubated with other bacteria at two initial inoculum densities [27]. Positive impacts on C. jejuni adhesion might be due to its increased growth or increased biomass, to its co-aggregation with other bacteria to form clusters that can deposit on the surfaces to initiate colonization, or to larger amounts of additional extracellular matrices of other species that can provide micro-niches in multispecies biofilms [32,33]. Additionally, the metabolic by-products of one organism might serve to support the growth of another, while the adhesion of one species might provide ligands that promote the attachment of others [34].…”

Diversity-Generating Machines: Genetics of Bacterial Sugar-Coating

“…As demonstrated in S. enterica , these predators exhibit different feeding preferences towards different O-antigens [91] . The specificity of such recognitions between a bacterivorous amoeba, Acanthamoeba castellanii , and E. coli has been attributed to the interaction between LPS and the predator’s surface mannose-binding protein [92] . Given the genetically characterised diversity of mannose N-glycans between different species of amoebae [93] , it is plausible that such interactions have shaped (at least partly) the diversity of O-antigens in some bacteria, as has been argued previously [64] .…”