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Proteomic and genomic analysis reveals novel Campylobacter jejuni outer membrane proteins and potential heterogeneity.

ABSTRACT: Gram-negative bacterial outer membrane proteins play important roles in the interaction of bacteria with their environment including nutrient acquisition, adhesion and invasion, and antibiotic resistance. In this study we identified 47 proteins within the Sarkosyl-insoluble fraction of Campylobacter jejuni 81-176, using LC-ESI-MS/MS. Comparative analysis of outer membrane protein sequences was visualised to reveal protein distribution within a panel of Campylobacter spp., identifying several C. jejuni-specific proteins. Smith-Waterman analyses of C. jejuni homologues revealed high sequence conservation amongst a number of hypothetical proteins, sequence heterogeneity of other proteins and several proteins which are absent in a proportion of strains.

SUBMITTER: Watson E

PROVIDER: S-EPMC4975774 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Proteomic and genomic analysis reveals novel Campylobacter jejuni outer membrane proteins and potential heterogeneity.

Watson Eleanor E Sherry Aileen A Inglis Neil F NF Lainson Alex A Jyothi Dushyanth D Yaga Raja R Manson Erin E Imrie Lisa L Everest Paul P Smith David G E DG

EuPA open proteomics 20140626

Gram-negative bacterial outer membrane proteins play important roles in the interaction of bacteria with their environment including nutrient acquisition, adhesion and invasion, and antibiotic resistance. In this study we identified 47 proteins within the Sarkosyl-insoluble fraction of Campylobacter jejuni 81-176, using LC-ESI-MS/MS. Comparative analysis of outer membrane protein sequences was visualised to reveal protein distribution within a panel of Campylobacter spp., identifyi ...[more]

PMID: 27525220

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Project description: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.Biological significanceThis 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.

Project description:The proteomes of outer membrane vesicles (OMVs) secreted by C. jejuni 81-176 strain, which was exposed to oxygen or antibiotic stress (polymyxin B), were characterized. We also assessed the OMVs production and their content in two mutated strains - ∆dsbI and ∆htrA. OMVs production was significantly increased under the polymyxin B stress and remained unaltered in all other variants. Interestingly, the qualitative load of OMVs was constant regardless of the stress conditions or genetic background. However, certain proteins exhibited notable quantitative changes, ranging from 4-fold decrease to 10-fold increase. Up- or downregulated proteins (e.g. major outer membrane protein porA, iron ABC transporter, serine protease- htrA, 60 kDa chaperonin-groL, enolase) represented various cell compartments (cytoplasm, periplasm, and membrane) and exhibited various functions; nevertheless, one common group was noted that consisted of components of flagellar apparatus, i.e., FlaA/B, FlgC/E, which were mostly upregulated. Some of these proteins are the putative substrates of DsbI protein. Further investigation of the regulation of C. jejuni OMVs composition and their role in virulence will allow a better understanding of the infectious process of C. jejuni.The proteomes of outer membrane vesicles (OMVs) secreted by C. jejuni 81–176 strain, which was exposed to oxygen or antibiotic stress (polymyxin B), were characterized. We also assessed the OMVs production and their content in two mutated strains – ∆dsbI and ∆htrA. OMVs production was significantly increased under the polymyxin B stress and remained unaltered in all other variants. Interestingly, the qualitative load of OMVs was constant regardless of the stress conditions or genetic background. However, certain proteins exhibited notable quantitative changes, ranging from 4-fold decrease to 10-fold increase. Up- or downregulated proteins (e.g. major outer membrane protein porA, iron ABC transporter, serine protease- htrA, 60 kDa chaperonin-groL, enolase) represented various cell compartments (cytoplasm, periplasm, and membrane) and exhibited various functions; nevertheless, one common group was noted that consisted of components of flagellar apparatus, i.e., FlaA/B, FlgC/E, which were mostly upregulated. Some of these proteins are the putative substrates of DsbI protein. Further investigation of the regulation of C. jejuni OMVs composition and their role in virulence will allow a better understanding of the infectious process of C. jejuni.

Project description:We cloned and expressed in Escherichia coli a gene encoding an 18-kDa outer membrane protein (Omp18) from Campylobacter jejuni ATCC 29428. The nucleotide sequence of the gene encoding Omp18 was determined, and an open reading frame of 165 amino acids was revealed. The amino acid sequence had the typical features of a leader sequence and a signal peptidase II cleavage site at the N-terminal part of Omp18. Moreover, the sequence had a high degree of similarity to the peptidoglycan-associated outer membrane lipoprotein P6 of Haemophilus influenzae and the peptidoglycan-associated lipoprotein PAL of E. coli. Southern blot analysis in which the cloned gene was used as a probe revealed genes similar to that encoding Omp18 in all species of the thermophilic group of campylobacters as well as Campylobacter sputorum. All campylobacters tested expressed a protein with a molecular mass identical to that of Omp18. The protein reacted immunologically with polyclonal antibodies directed against Omp18 from C. jejuni. PCR amplification of the gene encoding Omp18 with specific primers and subsequent restriction enzyme analysis of the amplified DNA fragments showed that the gene for Omp18 is highly conserved in C. jejuni strains isolated from humans, dogs, cats, calves, and chickens but is different in other Campylobacter species. In order to obtain pure recombinant Omp18 protein for serological assays, the cloned gene for Omp18 was genetically modified by replacing the signal sequence with a DNA segment encoding six adjacent histidine residues. Expression of this construct in E. coli allowed purification of the modified protein (Omp18-6xHis) by metal chelation chromatography. Sera from patients with past C. jejuni infection reacted positively with Omp18-6xHis, while sera from healthy blood donors showed no reaction with this antigen. Omp18, which is an outer membrane protein belonging to the family of PALs is well conserved in C. jejuni and is highly immunogenic. It is therefore a good candidate as an antigen for the serological diagnosis of past C. jejuni infections.

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Proteomic and genomic analysis reveals novel Campylobacter jejuni outer membrane proteins and potential heterogeneity.

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Proteomic and genomic analysis reveals novel <i>Campylobacter jejuni</i> outer membrane proteins and potential heterogeneity.

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