Activation of the l-fucose utilization cluster in induces proteomic changes and enhances Caco-2 cell invasion and fibronectin binding.

Most isolates carry the fucose utilization cluster () that supports the metabolism of l-fucose and d-arabinose. In this study we quantified l-fucose and d-arabinose metabolism and metabolite production, and the impact on Caco-2 cell interaction and binding to fibronectin, using NCTC11168 and the closely related human isolate strain 286. When cultured with l-fucose and d-arabinose, both isolates showed increased survival and production of acetate, pyruvate and succinate, and the respective signature metabolites lactate and glycolic acid, in line with an overall upregulation of l-fucose cluster proteins. Caco-2 cell studies and fibronectin-binding experiments showed a trend towards higher invasion and a significantly higher fibronectin binding efficacy of NCTC11168 cells grown with l-fucose and d-arabinose, while no significant differences were found with 286. Both fibronectin binding proteins, CadF and FlpA, were detected in the two isolates, but were not significantly differentially expressed in l-fucose or d-arabinose grown cells. Comparative proteomics analysis linked the NCTC11168 phenotypes uniquely to the more than 135-fold upregulated protein Cj0608, putative TolC-like component MacC, which, together with the detected Cj0606 and Cj0607 proteins, forms the tripartite secretion system MacABC with putative functions in antibiotic resistance, cell envelope stress response and virulence in Gram negative pathogenic bacteria. Further studies are required to elucidate the role of the MacABC system in cell surface structure modulation and virulence.