The variation of dTDP-l-rhamnose pathway genes in Vibrio cholerae

Li, Qun; Hobbs, Matthew; Reeves, Peter R.

doi:10.1099/mic.0.26382-0

Cited by 28 publications

(35 citation statements)

References 32 publications

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“…Of the 12 conserved ORFs described previously (35), the D class contains only the four anchor ORFs 1 and 2 (waaC and htrB) and 12 and 13 (waaV and waaF). Instead, this class shares genes similar to those required for dTDP-rhamnose biosynthesis in several bacteria (28,29,45), i.e., rmlA and rmlB homologues, and lacks the neuABC genes (required for sialic acid biosynthesis) (14,15,30) and the cst-encoded sialyltransferases involved with LOS sialylation (14). The lack of neu and cst genes thus correlates with the lack of sialic acid in the LOS of ATCC 43431, as has been reported previously (2).…”

Section: Resultssupporting

confidence: 62%

Identification ofCampylobacter jejuniATCC 43431-Specific Genes by Whole Microbial Genome Comparisons

2004

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This study describes a novel approach to identify unique genomic DNA sequences from the unsequenced strain C. jejuni ATCC 43431 by comparison with the sequenced strain C. jejuni NCTC 11168. A shotgun DNA microarray was constructed by arraying 9,600 individual DNA fragments from a C. jejuni ATCC 43431 genomic library onto a glass slide. DNA fragments unique to C. jejuni ATCC 43431 were identified by competitive hybridization to the array with genomic DNA of C. jejuni NCTC 11168. The plasmids containing unique DNA fragments were sequenced, allowing the identification of up to 130 complete and incomplete genes. Potential biological roles were assigned to 66% of the unique open reading frames. The mean G؉C content of these unique genes (26%) differs significantly from the G؉C content of the entire C. jejuni genome (30.6%). This suggests that they may have been acquired through horizontal gene transfer from an organism with a G؉C content lower than that of C. jejuni. Because the two C. jejuni strains differ by Penner serotype, a large proportion of the unique ATCC 43431 genes encode proteins involved in lipooligosaccharide and capsular biosynthesis, as expected. Several unique open reading frames encode enzymes which may contribute to genetic variability, i.e., restriction-modification systems and integrases. Interestingly, many of the unique C. jejuni ATCC 43431 genes show identity with a possible pathogenicity island from Helicobacter hepaticus and components of a potential type IV secretion system. In conclusion, this study provides a valuable resource to further investigate Campylobacter diversity and pathogenesis.

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Section: Resultssupporting

confidence: 62%

Identification ofCampylobacter jejuniATCC 43431-Specific Genes by Whole Microbial Genome Comparisons

2004

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“…L-Rhamnose requires four rml genes that generally appear in the order rmlBADC (37). Li et al (29) reported that these genes often are involved in recombination within V. cholerae if both donor and recipient have rml genes. In six V. cholerae isolates (O31, TMA21, O39, O12, 623-39, and O14), rmlBADC appear at the beginning of the region (Fig.…”

Section: Resultsmentioning

confidence: 99%

Genetic Diversity of O-Antigen Biosynthesis Regions in Vibrio cholerae

Aydanian

Tang

Morris

et al. 2011

Appl Environ Microbiol

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O-antigen biosynthetic (wbf) regions for Vibrio cholerae serogroups O5, O8, and O108 were isolated and sequenced. Sequences were compared to those of other published V. cholerae O-antigen regions. These wbf regions showed a high degree of heterogeneity both in gene content and in gene order. Genes identified frequently showed greater similarities to polysaccharide biosynthesis genes from species other than V. cholerae. Our results demonstrate the plasticity of O-antigen genes in V. cholerae, the diversity of the genetic pool from which they are drawn, and the likelihood that new pandemic serogroups will emerge.Cholera is a pandemic diarrheal disease that continues to be an important cause of morbidity and mortality worldwide. Cholera is associated with a clonally related subset of Vibrio cholerae strains, which carry ctxAB (cholera toxin subunits A and B), the vibrio pathogenicity island (VPI), and other cholera-associated genes (15,40). Until 1992, only serogroup O1 (out of more than 206 serogroups currently described) was recognized as a cause of cholera. In 1992, a new, non-O1 V. cholerae strain (subsequently designated V. cholerae O139) appeared in India and rapidly spread across much of Asia (32). Extensive studies (5,12,31,41) demonstrated that the O139 strain was closely related to the O1 El Tor strains of the 7th pandemic, except that the genes responsible for O1-antigen biosynthesis were deleted and replaced with DNA that encodes the O139 antigen. Since the O antigen is the major protective epitope, its alteration was sufficient to allow O139 strains to move in epidemic form through populations previously immune to cholera caused by O1. Thus, adults were more commonly affected than children (1). Recent studies suggest that the pandemic cluster carries other serogroups as well, including O37, O27, O53, O65, and O75 (31, 40, 43). These observations are consistent with the hypothesis that pathogenic V. cholerae strains are able to easily acquire and/or exchange O-antigen genes, with the new O antigen allowing strains to evade preexisting immunity to cholera.Changes in O-antigen structure also may provide selective advantages in the environment. During epidemics, bacteriophage may play a crucial role in controlling the number of V. cholerae in the environment (19), and since the O-antigen may serve as bacteriophage receptors, serogroup conversion also may be beneficial for evading phage predation (33). It is well documented that mobile genetic elements, bacteriophage, and the competence of V. cholerae to take up and assimilate free DNA from the environment significantly contribute to genetic diversity in V. cholerae (18). Serogroup conversion was demonstrated while V. cholerae was growing on a chitin substrate (6). This transfer may have been facilitated by the JUMPstart sequence, which has nucleotide similarity to a DNA uptake signal that causes the preferential uptake of free DNA containing that sequence in the Pasteurellaceae and is present in front of a laterally transferred O-antigen region in V. chole...

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“…DNA sequence analysis revealed that strain TW19 contained a transposon insertion (lollipop symbol in Fig. 1B) in an ORF that encodes a predicted protein with significant homology to the RmlC protein of E. coli K-12 and V. cholerae (35). RmlC is a dTDP-4-dehydrorhamnose 3,5-epimerase involved in the biosynthesis of dTDP-rhamnose, a Immediately upstream, we identified three additional ORFs that also encode proteins with significant homology to enzymes involved in the biosynthesis of dTDP-rhamnose.…”

Section: Resultsmentioning

confidence: 99%

Novel Role of the Lipopolysaccharide O1 Side Chain in Ferric Siderophore Transport and Virulence of Vibrio anguillarum

Welch

Crosa

2005

Infect Immun

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From a library of approximately 20,000 transposon mutants, we have identified mutants affected in chromosomal genes involved in synthesis of the siderophore anguibactin, as well as in ferric anguibactin utilization. Genetic and sequence analyses of one such transport-defective mutant revealed that the transposon insertion occurred in an open reading frame (ORF) with homology to rmlC, a dTDP-rhamnose biosynthetic gene. This ORF resides within a cluster of four ORFs, all of which are predicted to function in the biosynthesis of this O side chain precursor. The same phenotype was seen in a mutant obtained by allelic exchange in rmlD, another ORF in this dTDP-rhamnose biosynthetic cluster. This mutation could be complemented with the wild-type rmlD gene, restoring both production of the O1 antigen side chain and ferric anguibactin transport. Presence of the O1 side chain was crucial for the resistance of Vibrio anguillarum to the bactericidal action of nonimmune serum from the fish host. Surprisingly, further analysis demonstrated that these mutations were pleiotropic, leading to a dramatic decrease in the levels of FatA, the outer membrane protein receptor for ferric anguibactin transport, and a concomitant reduction in iron transport. Thus, our results in this work demonstrate that the lipopolysaccharide O1 side chain is required for the operation of two critical virulence factors in V. anguillarum: serum resistance and anguibactin-mediated iron transport. These factors allow V. anguillarum to survive in serum and multiply in the iron-limiting milieu of the host vertebrate.

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The variation of dTDP-l-rhamnose pathway genes in Vibrio cholerae

Cited by 28 publications

References 32 publications

Identification ofCampylobacter jejuniATCC 43431-Specific Genes by Whole Microbial Genome Comparisons

Identification ofCampylobacter jejuniATCC 43431-Specific Genes by Whole Microbial Genome Comparisons

Genetic Diversity of O-Antigen Biosynthesis Regions in Vibrio cholerae

Novel Role of the Lipopolysaccharide O1 Side Chain in Ferric Siderophore Transport and Virulence of Vibrio anguillarum

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