EptC of Campylobacter jejuni Mediates Phenotypes Involved in Host Interactions and Virulence

Section of Molecular Genetics and Microbiology.
Infection and immunity (Impact Factor: 3.73). 11/2012; 81(2). DOI: 10.1128/IAI.01046-12
Source: PubMed


Campylobacter jejuni is a natural commensal of the avian intestinal tract. However, the bacterium is also the leading cause of acute bacterial
diarrhea worldwide and is implicated in development of Guillain-Barré syndrome. Like many bacterial pathogens, C. jejuni assembles complex surface structures that interface with the surrounding environment and are involved in pathogenesis. Recent
work in C. jejuni identified a gene encoding a novel phosphoethanolamine (pEtN) transferase, EptC (Cj0256), that plays a promiscuous role in
modifying the flagellar rod protein, FlgG; the lipid A domain of lipooligosaccharide (LOS); and several N-linked glycans. In this work, we report that EptC catalyzes the addition of pEtN to the first heptose sugar of the inner
core oligosaccharide of LOS, a fourth enzymatic target. We also examine the role pEtN modification plays in circumventing
detection and/or killing by host defenses. Specifically, we show that modification of C. jejuni lipid A with pEtN results in increased recognition by the human Toll-like receptor 4–myeloid differentiation factor 2 (hTLR4-MD2)
complex, along with providing resistance to relevant mammalian and avian antimicrobial peptides (i.e., defensins). We also
confirm the inability of aberrant forms of LOS to activate Toll-like receptor 2 (TLR2). Most exciting, we demonstrate that
strains lacking eptC show decreased commensal colonization of chick ceca and reduced colonization of BALB/cByJ mice compared to wild-type strains.
Our results indicate that modification of surface structures with pEtN by EptC is key to its ability to promote commensalism
in an avian host and to survive in the mammalian gastrointestinal environment.

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