Campylobacter jejuni, from the delta-epsilon group of proteobacteria, is a microaerophilic, Gram-negative, flagellate, spiral bacterium—properties it shares with the related gastric pathogen Helicobacter pylori. It is the leading cause of bacterial food-borne diarrhoeal disease throughout the world1. In addition, infection with C. jejuni is the most frequent antecedent to a form of neuromuscular paralysis known as Guillain–Barre syndrome2. Here we report the genome sequence of C. jejuni NCTC11168. C. jejuni has a circular chromosome of 1,641,481 base pairs (30.6% G+C) which is predicted to encode 1,654 proteins and 54 stable RNA species. The genome is unusual in that there are virtually no insertion sequences or phage-associated sequences and very few repeat sequences. One of the most striking findings in the genome was the presence of hypervariable sequences. These short homopolymeric runs of nucleotides were commonly found in genes encoding the biosynthesis or modification of surface structures, or in closely linked genes of unknown function. The apparently high rate of variation of these homopolymeric tracts may be important in the survival strategy of C. jejuni.

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The genome sequence of the food-borne pathogen Campylobacter jejuni reveals hypervariable sequences

Commensal and pathogenic microorganisms must resist the deleterious actions of bile in order to survive in the human gastrointestinal tract. Herein we review the current knowledge on the mechanisms by which Gram-positive and Gram-negative bacteria contend with bile stress. We describe the antimicrobial actions of bile, assess the variations in bile tolerance between bacterial genera and examine the interplay between bile stress and other stresses. The molecular mechanisms underlying bile tolerance are investigated and the relationship between bile and virulence is examined. Finally, the potential benefits of bile research are briefly discussed.

The interaction between bacteria and bile

Polyphosphate kinase (PPK), encoded by the ppk gene, is the principal enzyme in many bacteria for the synthesis of inorganic polyphosphate (poly P) from ATP. A knockout mutant in the ppk gene of Pseudomonas aeruginosa PAO1 is impaired in flagellar swimming motility on semisolid agar plates. The mutant is deficient in type IV pili-mediated twitching motility and in a “swarming motility” previously unobserved in P. aeruginosa. In swarming cultures, the polar monotrichous bacteria have differentiated into elongated and polar multitrichous cells that navigate the surface of solid media. All of the motility defects in the ppk mutant could be complemented by a plasmid harboring the ppk gene. Because bacterial motility is often crucial for their survival in a natural environment and for systemic infection inside a host, the dependence for motility on PPK reveals important roles for poly P in diverse processes such as biofilm formation, symbiosis, and virulence.

https://www.pnas.org/content/pnas/97/9/4885.full.pdf

Inorganic polyphosphate is needed for swimming, swarming, and twitching motilities of Pseudomonas aeruginosa

Campylobacter jejuni is a foodborne bacterial pathogen that is common in the developed world. However, we know less about its biology and pathogenicity than we do about other less prevalent pathogens. Interest in C. jejuni has increased in recent years as a result of the growing appreciation of its importance as a pathogen and the availability of new model systems and genetic and genomic technologies. C. jejuni establishes persistent, benign infections in chickens and is rapidly cleared by many strains of laboratory mouse, but causes significant inflammation and enteritis in humans. Comparing the different host responses to C. jejuni colonization should increase our understanding of this organism.

Campylobacter jejuni : molecular biology and pathogenesis

Yersinia enterocolitica, a gram-negative coccobacillus, comprises a heterogeneous group of bacterial strains recovered from animal and environmental reservoirs. The majority of human pathogenic strains are found among distinct serogroups (e.g. O:3, O:5,27, O:8, O:9) and contain both chromosome- and plasmid (60 to 75 kb)-mediated virulence factors that are absent in "avirulent" strains. While Y. enterocolitica is primarily a gastrointestinal tract pathogen, it may produce extraintestinal infections in hosts with underlying predisposing factors. Postinfection sequelae include arthritis and erythema nodosum, which are seen mainly in Europe among patients with serogroups O:3 and O:9 infection and HLA-B27 antigen. Y. enterocolitica is acquired through the oral route and is epidemiologically linked to porcine sources. Bacteremia is prominent in the setting of immunosuppression or in patients with iron overload or those being treated with desferrioxamine. metastatic foci following bacteremia are common and often involve the liver and spleen. Of particular concern is blood transfusion-related bacteremia. Evidence has accumulated substantiating the role of Y. enterocolitica as a food-borne pathogen that has caused six major outbreaks in the United States. The diagnosis of Y. enterocolitica gastroenteritis is best achieved through isolation of the bacterium on routine or selective bacteriologic media. When necessary, serogrouping, biogrouping, and assessment for plasmid-encoded virulence traits may aid in distinguishing virulent from "avirulent" strains. Epidemiologically, outside of identified food-borne outbreaks, the source (reservoir) of Y. enterocolitica in sporadic cases is speculative. Therefore, prevention and control measures are difficult to institute.

/pdf/yersinia-enterocolitica-the-charisma-continues-500ili9dvk.pdf

Yersinia enterocolitica: the charisma continues.

Campylobacter jejuni 81-176 pgl mutants impaired in general protein glycosylation showed reduced ability to adhere to and invade INT407 cells and to colonize intestinal tracts of mice.

https://iai.asm.org/content/iai/70/4/2242.full.pdf

Campylobacter Protein Glycosylation Affects Host Cell Interactions

Four motile, non-adherent and non-invasive mutants of Campylobacter jejuni 81-176 generated by a site-specific insertional mutagenesis scheme were characterized at the molecular level and all contained a duplication of the same region of the chromosome. When this region was cloned from wild-type 81-176 and transferred into 81-176 on a shuttle plasmid, the same non-invasive phenotype as the original mutants was observed, suggesting that the region contained a repressor of adherence and invasion. The smallest piece of DNA identified which was capable of repressing adherence and invasion was a 0.8 kb fragment encoding the cheY gene of C.jejuni. To confirm further that CheY was responsible for the observed non-adherent and non-invasive phenotypes, the cheY gene was inserted into the arylsulfatase gene of 81-176 to generate a strain with two chromosomal copies of cheY. This diploid strain displayed the same non-adherent and non-invasive phenotype as the original mutants. Insertional inactivation of the cheY gene in 81-176 resulted in an approx. threefold increase in adherence and invasion in vitro, but this strain was unable to colonize or cause disease in animals. The diploid cheY strain, although able to colonize mice, was attenuated in a ferret disease model.

CheY-mediated modulation of Campylobacter jejuni virulence.

M cells in the Peyer's patches may facilitate transport of pathogens such as Campylobacter jejuni from the intestine. We evaluated this hypothesis by using electron microscopy to examine Peyer's pa...

Selective association and transport of Campylobacter jejuni through M cells of rabbit Peyer's patches.

Two genes have been identified in Campylobacter coli VC167 which are required for the biosynthesis of post-translational modifications on flagellin proteins. The ptmA gene encodes a protein of predicted M(r) 28,486 which shows significant homology to a family of alcohol dehydrogenases from a variety of bacteria. The ptmB gene encodes a protein of predicted M(r) 26,598 with significant homology to CMP-N-acetylneuraminic acid synthetase enzymes involved in sialic acid capsular biosynthesis in Neisseria meninigitidis and Escherichia coli K1. Site-specific mutation of either ptmA or ptmB caused loss of reactivity with antisera specific to the post-translational modifications and a change in the isoelectric focusing fingerprints relative to the parent strains. Mutation of ptmB, but not of ptmA, caused a change in apparent M(r) of the flagellin subunit in SDS-PAGE gels. The ptmA and ptmB genes are present in other strains of Campylobacter. In a rabbit model the ptmA mutant showed a reduced ability to elicit protection against subsequent challenge with heterologous strains of the same Lior serotype compared to the parental wild-type strain. This suggests that the surface-exposed post-translational modifications may play a significant role in the protective immune response.

Identification and characterization of genes required for post-translational modification of Campylobacter coli VC167 flagellin.

Examination of strains of Campylobacter jejuni, Campylobacter coli, and Campylobacter fetus by electron microscopy revealed that they produced peritrichous pilus-like appendages when the bacteria were grown in the presence of bile salts. Various bile-salt supplements were used and it was found that deoxycholate and chenodeoxycholic acid caused a significant enhancement of pilus production and resulted in a highly aggregative phenotype. Morphologically, the pili were between 4 and 7 nm in width and were greater than 1 micron in length. A gene, termed pspA, which encodes a predicted protein resembling protease IV of Escherichia coli, was identified in C. jejuni strain 81-176. A site-specific insertional mutation within this gene resulted in the loss of pilus synthesis as determined by electron microscopy. Insertions upstream and downstream of the gene had no effect on pilus production. The non-piliated mutant of strain 81-176 showed no reduction in adherence to or invasion of INT 407 cells in vitro. However, this mutant, while still possessing the ability to colonize ferrets, caused significantly reduced disease symptoms in this animal model.

Donald H. Burr

Papers

Campylobacter Protein Glycosylation Affects Host Cell Interactions

CheY-mediated modulation of Campylobacter jejuni virulence.

Selective association and transport of Campylobacter jejuni through M cells of rabbit Peyer's patches.

Identification and characterization of genes required for post-translational modification of Campylobacter coli VC167 flagellin.

An environmentally regulated pilus‐like appendage involved in Campylobacter pathogenesis