scholarly journals Bacteroides fragilis NCTC9343 Produces at Least Three Distinct Capsular Polysaccharides: Cloning, Characterization, and Reassignment of Polysaccharide B and C Biosynthesis Loci

2000 ◽  
Vol 68 (11) ◽  
pp. 6176-6181 ◽  
Author(s):  
Michael J. Coyne ◽  
Wiltrud Kalka-Moll ◽  
Arthur O. Tzianabos ◽  
Dennis L. Kasper ◽  
Laurie E. Comstock
Keyword(s):  
Animal Models ◽  
Capsular Polysaccharide ◽  
Bacteroides Fragilis ◽  
Prototype Strain ◽  
Rodent Model ◽  
Type Structure ◽  
Capsular Polysaccharides ◽  
Chromosomal Deletion ◽  
Polysaccharide Complex

ABSTRACT Bacteroides fragilis produces a capsular polysaccharide complex (CPC) that is directly involved in its ability to induce abscesses. Two distinct capsular polysaccharides, polysaccharide A (PS A) and PS B, have been shown to be synthesized by the prototype strain for the study of abscesses, NCTC9343. Both of these polysaccharides in purified form induce abscesses in animal models. In this study, we demonstrate that the CPC of NCTC9343 is composed of at least three distinct capsular polysaccharides: PS A, PS B, and PS C. A previously described locus contains genes whose products are involved in the biosynthesis of PS C rather than PS B as was originally suggested. The actual PS B biosynthesis locus was cloned, sequenced, and found to contain 22 genes in an operon-type structure. A mutant with a large chromosomal deletion of the PS B biosynthesis locus was created so that the contribution of PS B to the formation of abscesses could be assessed in a rodent model. Although purified PS B can induce abscesses, removal of this polysaccharide does not attenuate the organism's ability to induce abscesses.

scholarly journals Immunochemical and Biological Characterization of Three Capsular Polysaccharides from a Single Bacteroides fragilisStrain

2001 ◽  
Vol 69 (4) ◽  
pp. 2339-2344 ◽  
Author(s):  
Wiltrud M. Kalka-Moll ◽  
Ying Wang ◽  
L. E. Comstock ◽  
Sylvia E. Gonzalez ◽  
Arthur O. Tzianabos ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Basic Structure ◽  
Structural Features ◽  
Capsular Polysaccharides ◽  
Polysaccharide Complex ◽  
Abdominal Abscesses ◽  
Colonic Flora ◽  
Surface Polysaccharides ◽  
Normal Human ◽  
Net Charges

ABSTRACT Although Bacteroides fragilis accounts for only 0.5% of the normal human colonic flora, it is the anaerobic species most frequently isolated from intra-abdominal and other infections with an intestinal source. The capsular polysaccharides of B. fragilis are part of a complex of surface polysaccharides and are the organism's most important virulence factors in the formation of intra-abdominal abscesses. Two capsular polysaccharides from strain NCTC 9343, PS A1 and PS B1, have been characterized structurally. Their most striking feature is a zwitterionic charge motif consisting of both positively and negatively charged substituent groups on each repeating unit. This zwitterionic motif is essential for abscess formation. In this study, we sought to elucidate structural features of the capsular polysaccharide complex of a commonly studied B. fragilisstrain, 638R, that is distinct from strain 9343. We sought a more general picture of the species to establish basic structure-activity and structure-biosynthesis relationships among abscess-inducing polysaccharides. Strain 638R was found to have a capsular polysaccharide complex from which three distinct carbohydrates could be isolated by a complex purification procedure. Compositional and immunochemical studies demonstrated a zwitterionic charge motif common to all of the capsular polysaccharides that correlated with their ability to induce experimental intra-abdominal abscesses. Of interest is the range of net charges of the isolated polysaccharides—from positive (PS C2) to balanced (PS A2) to negative (PS 3). Relationships among structural components of the zwitterionic polysaccharides and their molecular biosynthesis loci were identified.

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

2000 ◽  
Vol 68 (11) ◽  
pp. 6182-6188 ◽  
Author(s):  
Laurie E. Comstock ◽  
Annalisa Pantosti ◽  
Dennis L. Kasper
Keyword(s):  
Genetic Diversity ◽  
Capsular Polysaccharide ◽  
Bacteroides Fragilis ◽  
Hybridization Analysis ◽  
Clinical Isolates ◽  
Pcr Analysis ◽  
Capsular Polysaccharides ◽  
Genetic Approach ◽  
Polysaccharide Biosynthesis ◽  
Putative Aminotransferase

ABSTRACT A genetic approach was used to assess the heterogeneity of the capsular polysaccharide C (PS C) biosynthesis locus ofBacteroides 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. OnlycfiA + 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 ofwcgC (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.

scholarly journals Analysis of a Capsular Polysaccharide Biosynthesis Locus of Bacteroides fragilis

1999 ◽  
Vol 67 (7) ◽  
pp. 3525-3532 ◽  
Author(s):  
Laurie E. Comstock ◽  
Michael J. Coyne ◽  
Arthur O. Tzianabos ◽  
Annalisa Pantosti ◽  
Andrew B. Onderdonk ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Bacteroides Fragilis ◽  
Open Reading Frames ◽  
Capsular Polysaccharides ◽  
Nucleotide Sugar ◽  
Polysaccharide Biosynthesis ◽  
Abdominal Abscesses ◽  
Intra Abdominal Infection ◽  
Reading Frames ◽  
Nucleotide Sugar Biosynthesis

ABSTRACT A major clinical manifestation of infection with Bacteroides fragilis is the formation of intra-abdominal abscesses, which are induced by the capsular polysaccharides of this organism. Transposon mutagenesis was used to locate genes involved in the synthesis of capsular polysaccharides. A 24,454-bp region was sequenced and found to contain a 15,379-bp locus (designated wcf) with 16 open reading frames (ORFs) encoding products similar to those encoded by genes of other bacterial polysaccharide biosynthesis loci. Four genes encode products that are similar to enzymes involved in nucleotide sugar biosynthesis. Seven genes encode products that are similar to sugar transferases. Two gene products are similar toO-acetyltransferases, and two products are probably involved in polysaccharide transport and polymerization. The product of one ORF, WcfH, is similar to a set of deacetylases of the NodB family. Deletion mutants demonstrated that the wcf locus is necessary for the synthesis of polysaccharide B, one of the two capsular polysaccharides of B. fragilis 9343. The virulence of the polysaccharide B-deficient mutant was comparable to that of the wild type in terms of its ability to induce abscesses in a rat model of intra-abdominal infection.

scholarly journals TLR2-stimulating contaminants in glycoconjugate fractions prepared from Bacteroides fragilis

2017 ◽  
Vol 23 (5) ◽  
pp. 449-458 ◽  
Author(s):  
Masahito Hashimoto ◽  
Junpei Waki ◽  
Haruyuki Nakayama-Imaohji ◽  
Mami Ozono ◽  
Shuhei Hashiguchi ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Intestinal Flora ◽  
Bacteroides Fragilis ◽  
Hydrophobic Interaction Chromatography ◽  
Hot Water ◽  
Proteinase K ◽  
Capsular Polysaccharides ◽  
Wild Type ◽  
Almost All ◽  
Cell Surface Glycoconjugates

Bacteroides fragilis is a member of the normal intestinal flora and is involved in host immunostimulation via TLR2. On the bacterial cell surface, glycoconjugates, such as LPS and capsular polysaccharide A (PSA), have been reported to participate in host immunostimulation via TLR2. Previously, we identified a TLR2-stimulating lipoprotein in B. fragilis cells. In this study, we demonstrated that TLR2-stimulating principal molecules in glycoconjugate fractions prepared from B. fragilis are contaminating proteinous molecules, which may also be lipoproteins. The glycoconjugate fractions were prepared by phenol–hot water extraction of B. fragilis wild type and PSA-deficient strains, followed by hydrophobic interaction chromatography. TLR2-stimilating activities of the fractions were not affected by PSA deficiency. By in-gel TLR2-stimulation assay, molecules in high-molecular-mass area, where capsular polysaccharides were migrated, were found not to stimulate TLR2, but those in the range of 15–40 kDa were active. Further, proteinase K could digest the latter molecules and the TLR2-stimulating activities were migrated to the area of below 15 kDa. These results support that proteinous molecules, which are estimated to be lipoproteins, are responsible for almost all TLR2-stimulating activity in the glycoconjugate fractions prepared from B. fragilis.

scholarly journals The capsular polysaccharide of Bacteroides fragilis comprises two ionically linked polysaccharides.

1992 ◽  
Vol 267 (25) ◽  
pp. 18230-18235
Author(s):  
A.O. Tzianabos ◽  
A Pantosti ◽  
H Baumann ◽  
J.R. Brisson ◽  
H.J. Jennings ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Bacteroides Fragilis

scholarly journals Mutational analysis of genes implicated in LPS and capsular polysaccharide biosynthesis in the opportunistic pathogen Bacteroides fragilis

Microbiology ◽  
2009 ◽  
Vol 155 (4) ◽  
pp. 1039-1049 ◽  
Author(s):  
Sheila Patrick ◽  
Simon Houston ◽  
Zubin Thacker ◽  
Garry W. Blakely
Keyword(s):  
Capsular Polysaccharide ◽  
Mutational Analysis ◽  
Bacteroides Fragilis ◽  
Gene Clusters ◽  
Opportunistic Pathogen ◽  
Extracellular Polysaccharides ◽  
Phase Variable ◽  
Multiple Gene ◽  
Polysaccharide Biosynthesis ◽  
Group 1

The obligate anaerobe Bacteroides fragilis is a normal resident of the human gastrointestinal tract. The clinically derived B. fragilis strain NCTC 9343 produces an extensive array of extracellular polysaccharides (EPS), including antigenically distinct large, small and micro- capsules. The genome of NCTC 9343 encodes multiple gene clusters potentially involved in the biosynthesis of EPS, eight of which are implicated in production of the antigenically variable micro-capsule. We have developed a rapid and robust method for generating marked and markerless deletions, together with efficient electroporation using unmodified plasmid DNA to enable complementation of mutations. We show that deletion of a putative wzz homologue prevents production of high-molecular-mass polysaccharides (HMMPS), which form the micro-capsule. This observation suggests that micro-capsule HMMPS constitute the distal component of LPS in B. fragilis. The long chain length of this polysaccharide is strikingly different from classical enteric O-antigen, which consists of short-chain polysaccharides. We also demonstrate that deletion of a putative wbaP homologue prevents expression of the phase-variable large capsule and that expression can be restored by complementation. This suggests that synthesis of the large capsule is mechanistically equivalent to production of Escherichia coli group 1 and 4 capsules.

Implant Infections Due to Enterococci: Role of Capsular Polysaccharides and Biofilm

2005 ◽  
Vol 28 (11) ◽  
pp. 1079-1090 ◽  
Author(s):  
F. Fabretti ◽  
J. Huebner
Keyword(s):  
Antimicrobial Agents ◽  
Capsular Polysaccharide ◽  
Female Genital Tract ◽  
Teichoic Acid ◽  
Capsular Polysaccharides ◽  
Human Pathogens ◽  
Artificial Joints ◽  
Artificial Hearts ◽  
Intravascular Catheters ◽  
Enterococcal Infections

Enterococci are natural inhabitants of the gastrointestinal tract and of the female genital tract of humans and many animals. In recent years, enterococci have been increasingly recognized as important human pathogens causing infections associated with medical devices. Their resistance to most antimicrobial agents and their ability to form biofilm has contributed to the increasing incidence of nosocomial enterococcal infections. Enterococci possess a capsular polysaccharide composed of a glycerol-teichoic acid-like molecule consisting of repeating units of 6-α-D-glucose-1-2-glycerol-3-PO4, substituted on carbon 2 with a α-2,1-linked molecule of glucose. Using both immunologic and genetic data E. faecalis can be assigned to specific serotypes based on capsular polysaccharides. Clinical examples of foreign-body infections due to enterococci are described, comprising infections of artificial joints, implanted intravascular catheters, artificial hearts and artificial valves, stents, liquor shunt devices, and intraocular infections. Methods to prevent and/or treat enterococcal infections are presented.

scholarly journals From animal models to patients: the role of placental microRNAs, miR-210, miR-126, and miR-148a/152 in preeclampsia

2020 ◽  
Vol 134 (8) ◽  
pp. 1001-1025 ◽  
Author(s):  
Sonya Frazier ◽  
Martin W. McBride ◽  
Helen Mulvana ◽  
Delyth Graham
Keyword(s):  
Animal Models ◽  
Cell Types ◽  
Rodent Model ◽  
Hypertensive Disorder ◽  
Model Studies ◽  
Genetic Components ◽  
Immune Mediated ◽  
Hypertensive Disorder Of Pregnancy

Abstract Placental microRNAs (miRNAs) regulate the placental transcriptome and play a pathological role in preeclampsia (PE), a hypertensive disorder of pregnancy. Three PE rodent model studies explored the role of placental miRNAs, miR-210, miR-126, and miR-148/152 respectively, by examining expression of the miRNAs, their inducers, and potential gene targets. This review evaluates the role of miR-210, miR-126, and miR-148/152 in PE by comparing findings from the three rodent model studies with in vitro studies, other animal models, and preeclamptic patients to provide comprehensive insight into genetic components and pathological processes in the placenta contributing to PE. The majority of studies demonstrate miR-210 is upregulated in PE in part driven by HIF-1α and NF-κBp50, stimulated by hypoxia and/or immune-mediated processes. Elevated miR-210 may contribute to PE via inhibiting anti-inflammatory Th2-cytokines. Studies report an up- and downregulation of miR-126, arguably reflecting differences in expression between cell types and its multifunctional capacity. MiR-126 may play a pro-angiogenic role by mediating the PI3K-Akt pathway. Most studies report miR-148/152 family members are upregulated in PE. Evidence suggests they may inhibit DNA methylation of genes involved in metabolic and inflammatory pathways. Given the genetic heterogeneity of PE, it is unlikely that a single placental miRNA is a suitable therapeutic target for all patients. Investigating miRNAs in PE subtypes in patients and animal models may represent a more appropriate approach going forward. Developing methods for targeting placental miRNAs and specific placental cell types remains crucial for research seeking to target placental miRNAs as a novel treatment for PE.

Sign in / Sign up

Export Citation Format

Share Document