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Mol Cell Proteomics. 2019 Jan 7. pii: mcp.RA118.001199. doi: 10.1074/mcp.RA118.001199. [Epub ahead of print]

Proteomics reveals multiple phenotypes associated with N-linked glycosylation in Campylobacter jejuni.

Author information

1
The University of Sydney, Australia.
2
School of Life and Environmental Sciences, The University of Sydney, Australia stuart.cordwell@sydney.edu.au.

Abstract

Campylobacter jejuni is a major gastrointestinal pathogen generally acquired via consumption of poorly prepared poultry. N-linked protein glycosylation encoded by the pgl gene cluster targets >80 membrane proteins and is required for both non-symptomatic chicken colonization and full human virulence. Despite this, the biological functions of N-glycosylation remain unknown. We examined the effects of pgl gene deletion on the C. jejuni proteome using label-based liquid chromatography / tandem mass spectrometry (LC-MS/MS) and validation using data independent acquisition (DIA-SWATH-MS). We quantified 1359 proteins corresponding to ~84% of the C. jejuni NCTC 11168 genome, and 1080 of these were validated by DIA-SWATH-MS. Deletion of the pglB oligosaccharyltransferase (ΔpglB) resulted in a significant change in abundance of 185 proteins, 137 of which were restored to their wild-type levels by reintroduction of pglB (ΔpglB::ΔpglB). Deletion of pglB was associated with significantly reduced abundances of pgl targets and increased stress-related proteins, including ClpB, GroEL, GroES, GrpE and DnaK. pglB mutants demonstrated reduced survival following temperature (4°C and 46°C) and osmotic (150 mM NaCl) shock, and altered biofilm phenotypes compared to wild-type C. jejuni Targeted metabolomics established that pgl negative C. jejuni switched from aspartate (Asp) to proline (Pro) uptake and accumulated intracellular succinate related to proteome changes including elevated PutP/PutA (proline transport and utilization), and reduced DctA/DcuB (aspartate import and succinate export, respectively). ΔpglB chemotaxis to some substrates (Asp, glutamate, succinate and α-ketoglutarate) was reduced and associated with altered abundance of transducer-like (Tlp) proteins. Glycosylation negative C. jejuni were depleted of all respiration-associated proteins that allow the use of alternative electron acceptors under low oxygen. We demonstrate for the first time that N-glycosylation is required for a specific enzyme activity (Nap nitrate reductase) that is associated with reduced abundance of the NapAB glycoproteins. These data indicate a multi-factorial role for N-glycosylation in C. jejuni physiology.

KEYWORDS:

Bacteria; Bacterial pathogenesis; Glycoprotein Pathways*; Microbiology; N-Glycosylation; Stress response; Virulence

PMID:
30617158
DOI:
10.1074/mcp.RA118.001199
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