title: Comprehensive proteomic profiling of outer membrane vesicles from Campylobacter jejuni.
abstract: Gram-negative bacteria constitutively release outer membrane vesicles (OMVs) during cell growth that play significant roles in bacterial survival, virulence and pathogenesis. In this study, comprehensive proteomic analysis of OMVs from a human gastrointestinal pathogen Campylobacter jejuni NCTC11168 was performed using high-resolution mass spectrometry. The OMVs of C. jejuni NCTC11168 were isolated from culture supernatants then characterized using electron microscopy and dynamic light scattering revealing spherical OMVs of an average diameter of 50nm. We then identified 134 vesicular proteins using high-resolution LTQ-Orbitrap mass spectrometry. Subsequent functional analysis of the genes revealed the relationships of the vesicular proteins. Furthermore, known N-glycoproteins were identified from the list of the vesicular proteome, implying the potential role of the OMVs as a delivery means for biologically relevant bacterial glycoproteins. These results enabled us to elucidate the overall proteome profile of pathogenic bacterium C. jejuni and to speculate on the function of OMVs in bacterial infections and communication.
  
  
  CONCLUSIONS
  This work demonstrates the importance of understanding vesicular proteomes from a human pathogen Campylobacter jejuni. From the secreted outer membrane vesicles (OMVs) of C. jejuni NCTC11168, we found a variety of virulence factors and essential proteins for bacterial survival. Bioinformatics analysis of these proteins predicted functional enrichment and localization. The most highly enriched were redox enzymes, which are considered to be essential for survival in oxygen-limiting environments and are predicted to be on the twin-arginine translocation (Tat) pathway suggesting a role for this pathway in the biogenesis of OMVs. This study additionally implicates a biological role for N-linked glycoproteins in OMVs. These approaches allow for a better understanding of the physiology of this important human pathogen.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
authors.forename: Kyoung-Soon
authors.initials: KS
authors.lastname: Jang
authors.affiliation: Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sweredoski
authors.affiliation: Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
authors.forename: Robert L J
authors.initials: RL
authors.lastname: Graham
authors.affiliation: Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
authors.forename: Sonja
authors.initials: S
authors.lastname: Hess
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA. Electronic address: clemons@caltech.edu.
authors.forename: William M
authors.initials: WM
authors.lastname: Clemons
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016123:Campylobacter jejuni / Q000378:metabolism* / Q000472:pathogenicity; D006801:Humans; D013058:Mass Spectrometry; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D020543:Proteome
keywords: C. jejuni NCTC11168; Functional annotation; Outer membrane vesicle; Signal peptide; Virulence factor