Large Sequence Diversity within the Biosynthesis Locus and Common Biochemical Features of Campylobacter coli Lipooligosaccharides

Abstract

Despite the importance of lipooligosaccharides (LOSs) in the pathogenicity of campylobacteriosis, little is known about the genetic and phenotypic diversity of LOS in Campylobacter coli. In this study, we investigated the distribution of LOS locus classes among a large collection of unrelated C. coli isolates sampled from several different host species. Furthermore, we paired C. coli genomic information and LOS chemical composition for the first time to investigate possible associations between LOS locus class sequence diversity and biochemical heterogeneity. After identifying three new LOS locus classes, only 85% of the 144 isolates tested were assigned to a class, suggesting higher genetic diversity than previously thought. This genetic diversity is at the basis of a completely unexplored LOS structural heterogeneity. Mass spectrometry analysis of the LOSs of nine isolates, representing four different LOS classes, identified two features distinguishing C. coli LOS from that of Campylobacter jejuni. 2-Amino-2-deoxy-D-glucose (GlcN)-GlcN disaccharides were present in the lipid A backbone, in contrast to the ␤-1=-6-linked 3-diamino-2,3-dideoxy-D-glucopyranose (GlcN3N)-GlcN backbone observed in C. jejuni. Moreover, despite the fact that many of the genes putatively involved in 3-acylamino-3,6-dideoxy-D-glucose (Quip3NAcyl) were apparently absent from the genomes of various isolates, this rare sugar was found in the outer core of all C. coli isolates. Therefore, regardless of the high genetic diversity of the LOS biosynthesis locus in C. coli, we identified species-specific phenotypic features of C. coli LOS that might explain differences between C. jejuni and C. coli in terms of population dynamics and host adaptation. IMPORTANCEDespite the importance of C. coli to human health and its controversial role as a causative agent of Guillain-Barré syndrome, little is known about the genetic and phenotypic diversity of C. coli LOSs. Therefore, we paired C. coli genomic information and LOS chemical composition for the first time to address this paucity of information. We identified two species-specific phenotypic features of C. coli LOS, which might contribute to elucidating the reasons behind the differences between C. jejuni and C. coli in terms of population dynamics and host adaptation. C ampylobacteriosis is the most common bacterial foodborne disease in developed countries, with over 200,000 human cases being reported annually in the European Union alone (1). The true burden of the disease in the population is likely underestimated, as many infections result in mild gastroenteritis (1). Approximately 80% of reported infections are caused by Campylobacter jejuni, and 7 to 18% of cases are attributed to C. coli. Therefore, C. coli is among the five most important bacterial etiological agents of human gastroenteritis (2, 3).As in other Gram-negative bacteria, Campylobacter species cell surface glycoconjugates, including lipooligosaccharides (LOSs), play an important role in serum and bile resistance; resistanc...

Domestication ofCampylobacter jejuniNCTC 11168

“…A knockout mutant of the final gene in this block, Cj1333 , demonstrated compromised agglutination and reduced invasion (in INT-407 cells)[78]. This region of the C. jejuni genome is prone to recombination and has shown a high level of diversity and is often implicated in bacterial virulence [34, 35, 37, 79–82]. Isolate 17 was hyper-motile and also among the most invasive isolates when tested against chicken cell lines, but invaded human cell lines poorly ( Table 2 ).…”

Genetics behind the biosynthesis of nonulosonic acid containing lipooligosaccharides inCampylobacter coli

“…After cstVI, cstIV is the most common orthologue; being present in ∼38% of the genomes positive for a LOS associated GT-42. Previously, no evidence of Neu5Ac had been found in the LOS of strains containing a cstIV orthologue (29). This was to be expected as Neu5Ac biosynthesis genes are rarely present in strains carrying cstIV (19).…”

“…C. coli 73 possesses LOS locus class II, which contains a copy of cstIV and lacks sialic acid biosynthesis genes neuABC or other copies of putative sialyltransferases. However, strain 73 possesses the conserved biosynthesis pathways for both legionaminic (including legionaminic acid synthetase neuB2 ) and pseudaminic acid (including pseudaminic acid synthetase neuB3 ) in the flagella glycosylation region (29). C. coli 76339 harbours two copies of putative sialyltransferases: cstV as part of LOS locus class IX (Fig.…”

“…Chromosomal mutant strains of C. coli 76339 (19, 20) and C. coli 73 (19, 29) were generated by homologous recombination with suicide vectors containing genes inactivated by the insertion of an antibiotic resistance cassette. All recombinant plasmids and primers are shown in Supplemental material (Suppl.…”

“…LOS profiles were assessed by silver staining as described earlier (29). Additionally, LOS sensitivity to neuraminidase was assessed by treating crude LOS with 2 IU/ml of Clostridium perfringens neuraminidase (Sigma-Aldrich) overnight at 37 °C.…”