Quantitative analyses reveal novel roles for N-glycosylation in a major enteric bacterial pathogen

In eukaryotes glycosylation plays a role in proteome stability, protein quality control and modulating protein function, however, similar studies in bacteria are lacking. Here, we investigate the role of general protein glycosylation systems in bacteria using the enteropathogen Campylobacter jejuni as a well-defined example. By using a quantitative proteomics strategy, we were able to monitor changes in the C. jejuni proteome when glycosylation is disrupted. We demonstrate that in C. jejuni, N-glycosylation is essential to maintain proteome stability and protein quality control. These findings guided us to investigate the role of N-glycosylation in modulating bacterial cellular activities. In glycosylation deficient C. jejuni, the multidrug efflux pump and electron transport pathways were significantly impaired. In vivo, we demonstrate that fully glycosylation deficient C. jejuni were unable to colonise its natural avian host. These results provide the first evidence of a link between proteome stability and complex functions via a bacterial general glycosylation system.