DNA Sequence and Mutational Analyses of the pVir Plasmid of
            <i>Campylobacter jejuni</i>
            81-176

Bacon, David; Alm, Richard A.; Hu, Lan; Hickey, Thomas E.; Ewing, Cheryl P.; Batchelor, Roger A.; Trust, Trevor J.; Guerry, Patricia

doi:10.1128/iai.70.11.6242-6250.2002

Cited by 140 publications

(132 citation statements)

References 41 publications

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“…The closest known homologs of some tfs3 genes are needed in H. pylori for competence in natural transformation; more distant homologs form part of the cag PAI and contribute to virulence. There are also striking homologies with genes in a virulence plasmid of Campylobacter jejuni that are needed for this pathogen's intracellular growth and competence for transformation (10). Our mutational test did not support a possible tfs3 involvement in transformation, nor was an association of tfs3 carriage and overt disease detected: tfs3 was either entirely absent or was present only in truncated form in several strains that can persist in cultured epithelial cells and was absent from a strain that acts as a donor in conjugation.…”

Section: Discussionmentioning

confidence: 99%

Cluster of Type IV Secretion Genes inHelicobacter pylori's Plasticity Zone

et al. 2003

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Some genes present in only certain strains of the genetically diverse gastric pathogen Helicobacter pylori may affect its phenotype and/or evolutionary potential. Here we describe a new 16.3-kb segment, 7 of whose 16 open reading frames are homologs of type IV secretion genes (virB4, virB7 to virB11, and virD4), the third such putative secretion gene cluster found in H. pylori. This segment, to be called tfs3, was discovered by subtractive hybridization and chromosome walking. Full-length and truncated tfs3 elements were found in 20 and 19%, respectively, of 94 strains tested, which were from Spain, Peru, India, and Japan. A tfs3 remnant (6 kb) was found in an archived stock of reference strain J99, although it was not included in this strain's published genome sequence. PCR and DNA sequence analyses indicated the following. (i) tfs3's ends are conserved. (ii) Right-end insertion occurred at one specific site in a chromosomal region that is varied in gene content and arrangement, the "plasticity zone." (iii) Left-end insertion occurred at different sites in each of nine strains studied. (iv) Sequences next to the right-end target in tfs3-free strains were absent from most strains carrying full-length tfs3 elements. These patterns suggested insertion by a transposition-like event, but one in which targets are chosen with little or no specificity at the left end and high specificity at the right end, thereby deleting the intervening DNA.

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Section: Discussionmentioning

confidence: 99%

Cluster of Type IV Secretion Genes inHelicobacter pylori's Plasticity Zone

et al. 2003

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“…jejuni strain 81-176 possesses two plasmids, one of which, pVir, is nonconjugative and affects both virulence and natural competence (2). Sequence analysis of this plasmid revealed the presence of eight genes with greatest homology to a type IV secretion system (TFSS) subsequently shown to be present in the ruminant commensal Wolinella succinogenes (1,3). There is also significant homology to two TFSS found in Helicobacter pylori.…”

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confidence: 98%

“…TFSS, which are present in a variety of plant and mammalian pathogens, are involved in the transfer of DNA, protein, or nucleoprotein complexes across bacterial membranes (8). The TFSS genes present on pVir have been proposed to encode proteins that form a functional secretion channel that appears to affect both intestinal epithelial cell invasion and natural competence (2,3).…”

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confidence: 99%

N-Linked Protein Glycosylation Is Required for Full Competence in Campylobacter jejuni 81-176

2004

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The recent sequencing of the virulence plasmid of Campylobacter jejuni 81-176 revealed the presence of genes homologous to type IV secretion systems (TFSS) that have subsequently been found in Helicobacter pylori and Wolinella succinogenes. Mutational analyses of some of these genes have implicated their involvement in intestinal epithelial cell invasion and natural competence. In this report, we demonstrate that one of these type IV secretion homologs, Cjp3/VirB10, is a glycoprotein. Treatment with various glycosidases and binding to soybean agglutinin indicated that the structure of the glycan present on VirB10 contains a terminal GalNAc, consistent with previous reports of N-linked glycans in C. jejuni. Site-directed mutagenesis of five putative N-linked glycosylation sites indicated that VirB10 is glycosylated at two sites, N32 and N97. Mutants in the N-linked general protein glycosylation (pgl) system of C. jejuni are significantly reduced in natural transformation, which is likely due, in part, to lack of glycosylation of VirB10. The natural transformation defect in a virB10 mutant can be complemented in trans by using a plasmid expressing wild-type VirB10 or an N32A substitution but not by using a mutant expressing VirB10 with an N97A substitution. Taken together, these results suggest that glycosylation of VirB10 specifically at N97 is required for the function of the TFSS and for full competence in C. jejuni 81-176.

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“…Type IV systems, for example the cag pathogenicity island of H. pylori, also are used by bacterial pathogens to inject substrates into the cytosol of target cells. C. jejuni pVir is a 37-kb plasmid that has been shown to harbor 54 predicted open reading frames (89). Mutations in some of the plasmid-encoded genes reduced invasion compared with the parental strain in vitro.…”

Section: It Is Not Yet Clear What Role Cdt Plays In Infection In Vivomentioning

confidence: 99%