Interstrain Variation of the Polysaccharide B Biosynthesis Locus of
            <i>Bacteroides fragilis</i>
            : Characterization of the Region from Strain 638R

Comstock, Laurie E.; Coyne, Michael J.; Tzianabos, Arthur O.; Kasper, Dennis L.

doi:10.1128/jb.181.19.6192-6196.1999

Cited by 16 publications

(8 citation statements)

References 18 publications

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“…The deduced amino acid sequence of ORFG102, including 12 transmembrane segments distributed throughout the protein, shows similarity to both the O antigen ligase WaaL (Heinrichs et al, 1998) and the O-polysaccharide polymerase Wzy (Comstock et al, 1999).…”

Section: Genetic Characterization Of the Slg Gene Clustermentioning

confidence: 96%

S-layer glycan-specific loci on the chromosome of Geobacillus stearothermophilus NRS 2004/3a and dTDP-l-rhamnose biosynthesis potential of G. stearothermophilus strains

et al. 2004

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The~16?5 kb surface layer (S-layer) glycan biosynthesis (slg) gene cluster of the Gram-positive thermophile Geobacillus stearothermophilus NRS 2004/3a has been sequenced. The cluster is located immediately downstream of the S-layer structural gene sgsE and consists of 13 ORFs that have been identified by database sequence comparisons. The cluster encodes dTDP-L-rhamnose biosynthesis (rml operon), required for building up the polyrhamnan S-layer glycan, as well as for assembly and export of the elongated glycan chain, and its transfer to the S-layer protein. This is the first report of a gene cluster likely to be involved in the glycosylation of an S-layer protein. There is evidence that this cluster is transcribed as a polycistronic unit, whereas sgsE is transcribed monocistronically. To get insights into the regulatory mechanisms underlying glycosylation of the S-layer protein, the influence of growth temperature on the S-layer was investigated in seven closely related G. stearothermophilus strains, of which only strain NRS 2004/3a possessed a glycosylated S-layer. Chromosomal DNA preparations of these strains were screened for the presence of the rml operon, because L-rhamnose is a frequent constituent of S-layer glycans. From rml-positive strains, flanking regions of the operon were sequenced. Comparison with the slg gene cluster of G. stearothermophilus NRS 2004/3a revealed sequence homologies between adjacent genes. The temperature inducibility of S-layer protein glycosylation was investigated in those strains by raising the growth temperature from 55 6C to 67 6C; no change of either the protein banding pattern or the glycan staining behaviour was observed on SDS-PAGE gels, although the sgsE transcript was several-fold more abundant at 67 6C. Cell-free extracts of the strains were capable of converting dTDP-D-glucose to dTDP-L-rhamnose. Taken together, the results indicate that the rml locus is highly conserved among G. stearothermophilus strains, and that in the investigated rml-containing strains, dTDP-L-rhamnose is actively synthesized in vitro. However, in contrast to previous reports for G. stearothermophilus wild-type strains, an increase in growth temperature did not switch an S-layer protein phenotype to an S-layer glycoprotein phenotype, via the de novo generation of a new S-layer gene sequence.

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Section: Genetic Characterization Of the Slg Gene Clustermentioning

confidence: 96%

S-layer glycan-specific loci on the chromosome of Geobacillus stearothermophilus NRS 2004/3a and dTDP-l-rhamnose biosynthesis potential of G. stearothermophilus strains

et al. 2004

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“…3(b)). Putative UDP-L L-FucNAc transferase genes are found to be located downstream and adjacent to fnl genes in other species, for example, in the Pseudomonas aeruginosa O11 gene cluster [22] and the Bacteroides fragilis CPS cluster [23]. This cassette-like region containing the fnl genes and putative UDP-L L-FucNAc transferase may facilitate lateral gene transfer of the genes.…”

Section: Escherichia Coli O4 and O26 Gene Cluster Organization And Ementioning

confidence: 99%

Evolutionary origins and sequence of theEscherichia coliO4 O-antigen gene cluster

D'Souza¹,

Samuel²,

Reeves³

2005

FEMS Microbiology Letters

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Escherichia coli express many types of O antigen, present in the outer membrane of the Gram-negative bacterial cell wall. O-Antigen biosynthesis genes are clustered together and differences seen in O-antigen types are due to genetic variation within this gene cluster. Sequencing of the E. coli O4 O-antigen gene cluster revealed a similar gene order and high levels of similarity to that of E. coli O26; indicating a common ancestor. These lateral transfer events observed within O-antigen gene clusters may occur as part of the evolution of the pathogenic clones.

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“…A product was amplified from all B. fragilis strains in PCR-1 and from all strains except the four cfiA ϩ strains in PCR-6. The DNA homology upstream of the 9343 and 638R PS C loci has been shown to continue into the first gene of each region, rmlA, and the two chromosomes begin to diverge at bp 338 of this gene (2). If this conserved portion of rmlA was present in the PS C locus of all B. fragilis strains, a product would be amplified from all strains in PCR-7.…”

Section: Pcr Analysis Of the Ps C Biosynthesis Regionmentioning

confidence: 99%

“…Each of these products likely transfers a positively charged free amino group to the repeating unit of PS C2. In addition, the locus contains a gene, wcgC, that has been shown by complementation to encode a UDP-N-acetylmannosamine dehydrogenase (2). WcgC converts UDP-N-acetylmannosamine to UDP-N-acetylmannosaminuronic acid, a negatively charged monosaccharide.…”

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confidence: 99%

Genetic Diversity of the Capsular Polysaccharide C Biosynthesis Region of Bacteroides fragilis

2000

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A genetic approach was used to assess the heterogeneity of the capsular polysaccharide C (PS C) biosynthesis locus of Bacteroides fragilis and to determine whether distinct loci contain genes whose products are likely to be involved in conferring charged groups that enable the B. fragilis capsular polysaccharides to induce abscesses. A collection of 50 B. fragilis strains was examined. PCR analysis demonstrated that the genes flanking the PS C biosynthesis region are conserved, whereas the genes within the loci are heterogeneous. Only cfiA ؉ B. fragilis strains, which represent 3% of the clinical isolates of B. fragilis, displayed heterogeneity in the regions flanking the polysaccharide biosynthesis genes. Primers were designed in the conserved regions upstream and downstream of the PS C locus and were used to amplify the region from 45 of the 50 B. fragilis strains studied. Fourteen PS C genetic loci could be differentiated by a combination of PCR and extended PCR. These loci ranged in size from 14 to 26 kb. Hybridization analysis with genes from the PS C loci of strains 9343 and 638R revealed that the majority of strains contain homologs of wcgC (N-acetylmannosamine dehydrogenase), wcfF (putative dehydrogenase), and wcgP (putative aminotransferase). The data suggest that the synthesis of polysaccharides that have zwitterionic characteristics rendering them able to induce abscesses is common in B. fragilis.

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Interstrain Variation of the Polysaccharide B Biosynthesis Locus of Bacteroides fragilis : Characterization of the Region from Strain 638R

Cited by 16 publications

References 18 publications

S-layer glycan-specific loci on the chromosome of Geobacillus stearothermophilus NRS 2004/3a and dTDP-l-rhamnose biosynthesis potential of G. stearothermophilus strains

S-layer glycan-specific loci on the chromosome of Geobacillus stearothermophilus NRS 2004/3a and dTDP-l-rhamnose biosynthesis potential of G. stearothermophilus strains

Evolutionary origins and sequence of theEscherichia coliO4 O-antigen gene cluster

Genetic Diversity of the Capsular Polysaccharide C Biosynthesis Region of Bacteroides fragilis

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