Essential genome of Campylobacter jejuni

Mandal, Rabindra K.; Jiang, Tieshan; Kwon, Young Min

doi:10.1186/s12864-017-4032-8

Cited by 31 publications

(18 citation statements)

References 58 publications

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“…A study on motility defects in C. jejuni has shown that the outcome of a deletion of one gene ( fla B) can be affected by second-site mutations in other genes ( fli W, and flg D) associated with the same phenotype ( de Vries et al, 2015 ). Based on recent studies, genes from the flagellar regulatory cascade were found essential for the fitness of C. jejuni 11168 during an in vitro growth experiment; fli F (MS ring); fli G (C-ring), fli L (motor); flg I and flg A (P-ring); flg B, flg C, flg G and fli E (rod); fli H and fli Q (T3SS); and flg P and prf B_flg (unknown function) ( de Vries et al, 2017 ; Mandal et al, 2017 ). Interestingly, although these genes are required for fitness in colonization of two different hosts, survival in a third host, and invasion of tissue culture cells, no mutations were detected in any of these genes in our experiment.…”

Section: Discussionmentioning

confidence: 99%

Experimental Evolution of Campylobacter jejuni Leads to Loss of Motility, rpoN (σ54) Deletion and Genome Reduction

et al. 2020

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Evolution experiments in the laboratory have focused heavily on model organisms, often to the exclusion of clinically relevant pathogens. The foodborne bacterial pathogen Campylobacter jejuni belongs to a genus whose genomes are small compared to those of its closest genomic relative, the free-living genus Sulfurospirillum, suggesting genome reduction during the course of evolution to host association. In an in vitro experiment, C. jejuni serially passaged in rich medium in the laboratory exhibited loss of flagellar motility-an essential function for host colonization. At early time points the motility defect was often reversible, but after 35 days of serial culture, motility was irreversibly lost in most cells in 5 independently evolved populations. Population re-sequencing revealed disruptive mutations to genes in the flagellar transcriptional cascade, rpoN (σ54)-therefore disrupting the expression of the genes σ54 regulates-coupled with deletion of rpoN in all evolved lines. Additional mutations were detected in virulencerelated loci. In separate in vivo experiments, we demonstrate that a phase variable (reversible) motility mutant carrying an adenine deletion within a homopolymeric tract resulting in truncation of the flagellar biosynthesis gene fliR was deficient for colonization in a C57BL/6 IL-10 −/− mouse disease model. Re-insertion of an adenine residue partially restored motility and ability to colonize mice. Thus, a pathogenic C. jejuni strain was rapidly attenuated by experimental laboratory evolution and demonstrated genomic instability during this evolutionary process. The changes observed suggest C. jejuni is able to evolve in a novel environment through genome reduction as well as transition, transversion, and slip-strand mutations.

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Section: Discussionmentioning

confidence: 99%

Experimental Evolution of Campylobacter jejuni Leads to Loss of Motility, rpoN (σ54) Deletion and Genome Reduction

et al. 2020

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“…Nonetheless, Cj1509 could control the expression of selected C. jejuni genes in response to unknown stimuli; however, Cj1509 has been reported to be non-essential in some strains ( de Vries et al, 2017 ). Moreover, in different laboratories, Cj1509 has been shown to be an essential and non-essential gene in the same strain, e.g., C. jejuni 11168 ( Metris et al, 2011 ; de Vries et al, 2017 ; Mandal et al, 2017 ). Thus, it is possible that strain-specific genome content and growth conditions determine the actual role of Cj1509 in C. jejuni physiology.…”

Section: Discussionmentioning

confidence: 99%

Structure and Function of the Campylobacter jejuni Chromosome Replication Origin

et al. 2018

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Campylobacter jejuni is the leading bacterial cause of foodborne infections worldwide. However, our understanding of its cell cycle is poor. We identified the probable C. jejuni origin of replication (oriC) – a key element for initiation of chromosome replication, which is also important for chromosome structure, maintenance and dynamics. The herein characterized C. jejuni oriC is monopartite and contains (i) the DnaA box cluster, (ii) the DnaA-dependent DNA unwinding element (DUE) and (iii) binding sites for regulatory proteins. The cluster of five DnaA boxes and the DUE were found in the dnaA-dnaN intergenic region. Binding of DnaA to this cluster of DnaA-boxes enabled unwinding of the DUE in vitro. However, it was not sufficient to sustain replication of minichromosomes, unless the cluster was extended by additional DnaA boxes located in the 3′ end of dnaA. This suggests, that C. jejuni oriC requires these boxes to initiate or to regulate replication of its chromosome. However, further detailed mutagenesis is required to confirm the role of these two boxes in initiation of C. jejuni chromosome replication and thus to confirm partial localization of C. jejuni oriC within a coding region, which has not been reported thus far for any bacterial oriC. In vitro DUE unwinding by DnaA was inhibited by Cj1509, an orphan response regulator and a homolog of HP1021, that has been previously shown to inhibit replication in Helicobacter pylori. Thus, Cj1509 might play a similar role as a regulator of C. jejuni chromosome replication. This is the first systematic analysis of chromosome replication initiation in C. jejuni, and we expect that these studies will provide a basis for future research examining the structure and dynamics of the C. jejuni chromosome, which will be crucial for understanding the pathogens’ life cycle and virulence.

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“…For the Km R marker strain, we selected 10 mutants randomly from the C . jejuni strain 11168 Tn5 transposon mutant library previously described by Mandal et al [ 56 ] and compared their natural transformation efficiency using genomic DNA of the C . jejuni Cm R marker strain.…”

Section: Methodsmentioning

confidence: 99%

Horizontal genetic exchange of chromosomally encoded markers between Campylobacter jejuni cells

Samarth

Kwon

2020

PLoS ONE

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Many epidemiological studies provide us with the evidence of horizontal gene transfer (HGT) contributing to the bacterial genomic diversity that benefits the bacterial populations with increased ability to adapt to the dynamic environments. Campylobacter jejuni , a major cause of acute enteritis in the U.S., often linked with severe post-infection neuropathies, has been reported to exhibit a non-clonal population structure and comparatively higher strain-level genetic variation. In this study, we provide evidence of the HGT of chromosomally encoded genetic markers between C . jejuni cells in the biphasic MH medium. We used two C . jejuni NCTC-11168 mutants harbouring distinct antibiotic-resistance genes [chloramphenicol (Cm) and kanamycin (Km)] present at two different neutral genomic loci. Cultures of both marker strains were mixed together and incubated for 5 hrs, then plated on MH agar plates supplemented with both antibiotics. The recombinant cells with double antibiotic markers were generated at the frequency of 0.02811 ± 0.0035% of the parental strains. PCR assays using locus-specific primers confirmed that transfer of the antibiotic-resistance genes was through homologous recombination. Also, the addition of chicken cecal content increased the recombination efficiency approximately up to 10-fold as compared to the biphasic MH medium (control) at P < 0.05. Furthermore, treating the co-culture with DNase I decreased the available DNA, which in turn significantly reduced recombination efficiency by 99.92% ( P < 0.05). We used the cell-free supernatant of 16 hrs-culture of Wild-type C . jejuni as a template for PCR and found DNA sequences from six different genomic regions were easily amplified, indicating the presence of released chromosomal DNA in the culture supernatant. Our findings suggest that HGT in C . jejuni is facilitated in the chicken gut environment contributing to in vivo genomic diversity. Additionally, C . jejuni might have an active mechanism to release its chromosomal DNA into the extracellular environment, further expediting HGT in C . jejuni populations.

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Essential genome of Campylobacter jejuni

Cited by 31 publications

References 58 publications

Experimental Evolution of Campylobacter jejuni Leads to Loss of Motility, rpoN (σ54) Deletion and Genome Reduction

Experimental Evolution of Campylobacter jejuni Leads to Loss of Motility, rpoN (σ54) Deletion and Genome Reduction

Structure and Function of the Campylobacter jejuni Chromosome Replication Origin

Horizontal genetic exchange of chromosomally encoded markers between Campylobacter jejuni cells

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