Campylobacter jejuni is the leading cause of bacterial gastroenteritis in the developed world, and is responsible for as many as 400 to 500 million cases a year worldwide. Human infection is predominantly caused by the consumption of improperly prepared poultry products. C. jejuni exists as an asymptomatic commensal organism within the intestines of chickens, but is virulent to humans. While the exact mechanisms underpinning this difference in pathogenicity remain unknown, factors such as motility and nutrient uptake are thought to play a role. Proteomics analysis of C. jejuni NCTC 11168 O under conditions that mimic human host environments (supplementation with deoxycholate [bile salts], the iron chelator deferroxamine, and high salt) identified Cj0025c as the most induced protein under such conditions (2.5-8.0-fold induction). Cj0025c encodes a putative sodium:dicarboxylate nutrient transporter. In order to help determine the function of Cj0025, a knockout mutant was analysed using a variety of techniques, including phenotypic and virulence assays and label-free SWATH proteomics. Deletion of cj0025c resulted in significantly reduced motility and invasion of human Caco-2 intestinal epithelial cells compared with wild-type. Assays employing dicarboxylates as sole carbon sources in minimal medium, combined with metabolomics, were used to identify Cj0025c-associated nutrients. Proteomics highlighted differences in protein abundance between knockout and wild-type C. jejuni, including those with functions in extracellular polysaccharide and lipopolysaccharide biosynthesis, possibly suggesting a role in cell-cell interactions and biofilm formation.