Identification and initial characterisation of a protein involved in Campylobacter jejuni cell shape

Abstract

Campylobacter jejuni is the leading cause of bacterial food borne illness. While helical cell shape is considered important for C. jejuni pathogenesis, this bacterium is capable of adopting other morphologies. To better understand how helical-shaped C. jejuni maintain their shape and thus any associated colonisation, pathogenicity or other advantage, it is first important to identify the genes and proteins involved. So far, two peptidoglycan modifying enzymes Pgp1 and Pgp2 have been shown to be required for C. jejuni helical cell shape. We performed a visual screen of ∼2000 transposon mutants of C. jejuni for cell shape mutants. Whole genome sequence data of the mutants with altered cell shape, directed mutants, wild type stocks and isolated helical and rod-shaped ‘wild type’ C. jejuni, identified a number of different mutations in pgp1 and pgp2, which result in a change in helical to rod bacterial cell shape. We also identified an isolate with a loss of curvature. In this study, we have identified the genomic change in this isolate, and found that targeted deletion of the gene with the change resulted in bacteria with loss of curvature. Helical cell shape was restored by supplying the gene in trans. We examined the effect of loss of the gene on bacterial motility, adhesion and invasion of tissue culture cells and chicken colonisation, as well as the effect on the muropeptide profile of the peptidoglycan sacculus. Our work identifies another factor involved in helical cell shape.

Genomic correlates of extraintestinal infection are linked with changes in cell morphology in Campylobacter jejuni

“…In addition, changes in cell shape and an alteration in peptidoglycan structure resulting from pgp1 and pgp2 mutations also altered levels of activation of human host cell receptors in response to infection [80, 93], indicating a possible advantage of the change in cell shape. An isolate showing a similar elongated helical morphology to that observed in our study, arising from mutation in a different gene ( Cj1564 ), showed decreased ability to migrate through agar and decreased ability to adhere to and invade Caco-2 cells, however, it showed no impairment in chick colonization [83]. These findings collectively indicate that cell shape variation could be adaptive in the systemic niche, though ability to colonize a new host could potentially be compromised.…”

“…Phase variation in pgp1 was observed in one gastrointestinal ST50 isolate, but pgp1 also carried unique nonsynonymous substitutions in H1604 and H1664 and a truncation in H1664. Similar to pgp1 , pgp2 is also involved in mediating cell morphology and deletion has been shown to cause a switch to rod-shaped morphology and defects in motility and biofilm formation, as well as impairment in a chick colonization model [ 83 ]. Because we identified mutations in both mreB and pgp1 , we examined the sequences for this gene as well.…”

Effect of Lactobacillus spp. on adhesion, invasion, and translocation of Campylobacter jejuni in chicken and pig small-intestinal epithelial cell lines

“…adverse conditions of the gastrointestinal tract, to finally colonise the jejunum and ileum of the host [4,5]. Adhesion to epithelial cells of the animal gastrointestinal tract is thus the first important step for successful colonisation.…”

Effect of Lactobacillus spp. on adhesion, invasion, and translocation of Campylobacter jejuni in chicken and pig small-intestinal epithelial cell lines

“…However, to establish an infection, Campylobacter spp. first adhere to and persist in the mucus layer that covers the intestinal epithelium, and thus survive the adverse conditions of the gastrointestinal tract, to finally colonise the jejunum and ileum of the host [4,5]. Adhesion to epithelial cells of the animal gastrointestinal tract is thus the first and important step for successful colonisation.…”