Morphology heterogeneity within a Campylobacter jejuni helical population: the use of calcofluor white to generate rod‐shaped C. jejuni 81‐176 clones and the genetic determinants responsible for differences in morphology within 11168 strains

• Published in: Molecular microbiology Vol. 104; no. 6; pp. 948 - 971
• Main Authors: Frirdich, Emilisa, Biboy, Jacob, Huynh, Steven, Parker, Craig T., Vollmer, Waldemar, Gaynor, Erin C.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.06.2017; John Wiley and Sons Inc
• Subjects: Bacteria; Bacterial Proteins - metabolism; Benzenesulfonates; Biological effects; Biological properties; Campylobacter; Campylobacter Infections - microbiology; Campylobacter jejuni - cytology; Campylobacter jejuni - genetics; Clone Cells; Colonization; Complementation; Correlation; Curvature; Defects; Deoxyribonucleic acid; DNA; DNA repair; Endopeptidases; Exposure; Frameshift mutation; Gene Expression Regulation, Bacterial - genetics; Gene sequencing; Genes; Genomes; Heterogeneity; Hydrolase; Mathematical analysis; Microorganisms; Morphology; Mutants; Mutation; Optimization; Pathogens; Peptidoglycan - metabolism; Peptidoglycan hydrolase; RecR gene; Repair; Single-nucleotide polymorphism; Survival; Transcription
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.13672

Summary Campylobacter jejuni helical shape is important for colonization and host interactions with straight mutants having altered biological properties. Passage on calcofluor white (CFW) resulted in C. jejuni 81‐176 isolates with morphology changes: either a straight morphology from frameshift mutations and single nucleotide polymorphisms in peptidoglycan hydrolase genes pgp1 or pgp2 or a reduction in curvature due a frameshift mutation in cjj81176_1105, a putative peptidoglycan endopeptidase. Shape defects were restored by complementation. Whole genome sequencing of CFW‐passaged strains showed no specific changes correlating to CFW exposure. The cjj81176_1279 (recR; recombinational DNA repair) and cjj81176_1449 (unknown function) genes were highly variable in all 81‐176 strains sequenced. A frameshift mutation in pgp1 of our laboratory isolate of the straight genome sequenced variant of 11168 (11168‐GS) was also identified. The PG muropeptide profile of 11168‐GS was identical to that of Δpgp1 in the original minimally passaged 11168 strain (11168‐O). Introduction of wild type pgp1 into 11168‐GS did not restore helical morphology. The recR gene was also highly variable in 11168 strains. Microbial cell‐to‐cell heterogeneity is proposed as a mechanism of ensuring bacterial survival in sub‐optimal conditions. In certain environments, changes in C. jejuni morphology due to genetic heterogeneity may promote C. jejuni survival. The helical shape of Campylobacter jejuni is critical for key pathogenic attributes. This study describes the appearance of mutations in the peptidoglycan carboxypeptidases pgp1 and pgp2 resulting in rod‐shaped cells, as well as in cjj81176_1105, a putative endopeptidase, resulting in a curved‐rod morphology. Morphological heterogeneity resulting from phase variation in PG‐modifying enzymes results in changes in the biological properties of C. jejuni, possibly providing a selective advantage under certain conditions.