Lightning Talks 29th Annual Lorne Proteomics Symposium 2024

Proteomics of Campylobacter jejuni exposed to altered environmental signals reveals changes consistent with remodelling of lipid A and nutrient acquisition (#109)

Tess E McEnearney 1 , Nova Mondry Cohen 1 , Joel A. Cain 1 , Lok Man 1 , Stuart J Cordwell 1 2
  1. School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW, Australia
  2. Sydney Mass Spectrometry, Camperdown, NSW, Australia

Campylobacter jejuni is a major zoonotic and foodborne human gastrointestinal pathogen. Disease largely results from consumption of contaminated water and poorly prepared or insufficiently cooked poultry products, as C. jejuni is considered an asymptomatic commensal in avian species. The organism is a Gram negative, helical, and motile bacterium that is characterised by unique biochemistry, including an atypical metabolism (reliance on amino and organic acids as carbon sources), the ability to post-translationally modify proteins by eukaryotic-like N- and O-linked glycosylation, and displays membrane and surface-associated structures that are not consistent with those found in other Gram-negative enteric bacteria. These surface structures likely play an essential role in colonisation, early survival in, and ultimately adaptation to, avian and human hosts. C. jejuni displays distinct variations of Gram-negative lipid A, lipooligosaccharide, peptidoglycan, and phospholipids, which all contribute to interactions with the environment. Here, we compared the C. jejuni proteome and lipidome at 37°C and 42°C (human and avian body temperature), in the presence or absence of H2O2 and paraquat-induced oxidative stress, as well as growth supplemented with chicken exudate (CE; a biofilm-inducing supplement representing conditions found on poultry products). Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS) showed diverse remodelling of lipid A in all growth conditions. In the presence of CE, C. jejuni produced preferentially mono-phosphorylated lipid A consistent with significantly reduced abundance of the lipid A kinase, LpxK; while at 42°C, we observed significantly reduced abundance of phosphoethanolamine (pEtN)-modified lipid A, despite detecting no changes to the abundance of the sole pEtN transferase EptC. These findings show that C. jejuni is capable of remodelling lipid A in response to altered growth signals.