Molecular characterization of the complete 23F capsular polysaccharide locus of Streptococcus pneumoniae.
Ontology highlight
ABSTRACT:
SUBMITTER: Ramirez M
PROVIDER: S-EPMC107572 | biostudies-literature | 1998 Oct
REPOSITORIES: biostudies-literature
Publications
Molecular characterization of the complete 23F capsular polysaccharide locus of Streptococcus pneumoniae.
Journal of bacteriology 19981001 19
The complete DNA sequence of the capsular locus 23F of Streptococcus pneumoniae is presented. The 18.6-kb cps23f locus is composed of 18 open reading frames flanked at the 5' and 3' ends by the genes dexB and aliA, an arrangement similar to those of some of the other identified cps loci. ...[more]
Similar Datasets
Project description:Streptococcus pneumoniae serogroup 10 includes four cross-reactive capsular polysaccharide (CPS) serotypes (10F, 10A, 10B, and 10C). In the present study, the structures of CPS10B and CPS10C were determined by chemical and high resolution NMR methods to define the features of each serotype. Both CPS10C and CPS10F had β1-6-linked Galf branches formed from the termini of linear repeating units by wzy-dependent polymerization through the 4-OH of subterminal GalNAc. The only difference between these polysaccharides was the wcrC-dependent α1-2 or wcrF-dependent α1-4 linkages between Gal and ribitol-5-phosphate. The presence of one linkage or the other also distinguished the repeating units of CPS10B and CPS10A. However, whereas these polysaccharides both had β1-3-linked Galf branches linked to GalNAc, only CPS10A had additional β1-6-linked Galp branches. These Galp branches and the reaction of a CPS10A-specific monoclonal antibody were eliminated by deletion of wcrG from the cps10A locus. In contrast, deletion of this gene from the cps10B locus had no effect on the structure of CPS10B, thereby identifying wcrG as a pseudogene in this serotype. The β1-3-linked Galf branches of CPS10A and CPS10B were eliminated by deletion of wcrD from each corresponding cps locus. Deletion of this gene also eliminated wcrG-dependent β1-6-linked Galp branches from CPS10A, thereby identifying WcrG as a branching enzyme that acts on the product of WcrD. These findings provide a complete view of the molecular, structural, and antigenic features of CPS serogroup 10, as well as insight into the possible emergence of new serotypes.
| S-EPMC3195564 | biostudies-literature
Project description:Although closely related at the molecular level, the capsular polysaccharide (CPS) of serotype 10F Streptococcus pneumoniae and coaggregation receptor polysaccharide (RPS) of Streptococcus oralis C104 have distinct ecological roles. CPS prevents phagocytosis of pathogenic S. pneumoniae, whereas RPS of commensal S. oralis functions as a receptor for lectin-like adhesins on other members of the dental plaque biofilm community. Results from high resolution NMR identified the recognition region of S. oralis RPS (i.e. Galfbeta1-6GalNAcbeta1-3Galalpha) in the hexasaccharide repeat of S. pneumoniae CPS10F. The failure of this polysaccharide to support fimbriae-mediated adhesion of Actinomyces naeslundii was explained by the position of Galf, which occurred as a branch in CPS10F rather than within the linear polysaccharide chain, as in RPS. Carbohydrate engineering of S. oralis RPS with wzy from S. pneumoniae attributed formation of the Galf branch in CPS10F to the linkage of adjacent repeating units through sub terminal GalNAc in Galfbeta1-6GalNAcbeta1-3Galalpha rather than through terminal Galf, as in RPS. A gene (wcrD) from serotype 10A S. pneumoniae was then used to engineer a linear surface polysaccharide in S. oralis that was identical to RPS except for the presence of a beta1-3 linkage between Galf and GalNAcbeta1-3Galalpha. This polysaccharide also failed to support adhesion of A. naeslundii, thereby establishing the essential role of beta1-6-linked Galf in recognition of adjacent GalNAcbeta1-3Galalpha in wild-type RPS. These findings, which illustrate a molecular approach for relating bacterial polysaccharide structure to function, provide insight into the possible evolution of S. oralis RPS from S. pneumoniae CPS.
| S-EPMC2911330 | biostudies-literature
Project description:Capsular polysaccharide (CPS) is a major virulence factor in Streptococcus pneumoniae. CPS gene clusters of S. pneumoniae types 4, 6B, 8, and 18C were sequenced and compared with those of CPS types 1, 2, 14, 19F, 19A, 23F, and 33F. All have the same four genes at the 5' end, encoding proteins thought to be involved in regulation and export. Sequences of these genes can be divided into two classes, and evidence of recombination between them was observed. Next is the gene encoding the transferase for the first step in the synthesis of CPS. The predicted amino acid sequences of these first sugar transferases have multiple transmembrane segments, a feature lacking in other transferases. Sugar pathway genes are located at the 3' end of the gene cluster. Comparison of the four dTDP-L-rhamnose pathway genes (rml genes) of CPS types 1, 2, 6B, 18C, 19F, 19A, and 23F shows that they have the same gene order and are highly conserved. There is a gradient in the nature of the variation of rml genes, the average pairwise difference for those close to the central region being higher than that for those close to the end of the gene cluster and, again, recombination sites can be observed in these genes. This is similar to the situation we observed for rml genes of O-antigen gene clusters of Salmonella enterica. Our data indicate that the conserved first four genes at the 5' ends and the relatively conserved rml genes at the 3' ends of the CPS gene clusters were sites for recombination events involved in forming new forms of CPS. We have also identified wzx and wzy genes for all sequenced CPS gene clusters by use of motifs.
| S-EPMC98014 | biostudies-literature
Project description:The polysaccharide capsule of Streptococcus pneumoniae is the main virulence factor, which makes the bacterium resistant to phagocytosis. Expression of capsular polysaccharide must be adjusted at different stages of pneumococcal infection, thus, their transcriptional regulation appears to be crucial. To get insight into the existence of regulatory mechanisms common to most serotypes, a bioinformatic analysis of the DNA region located upstream of the capsular locus was performed. With the exception of serotype 37, the capsular locus is located between dexB and aliA on the pneumococcal chromosome. Up to 26 different sequence organizations were found among pneumococci synthesizing their capsule through a Wzy-polymerase-dependent mechanism, mostly varying according to the presence/absence of distinct insertion elements. As a consequence, only approximately 250 bp (including a 107 bp RUP_A element) was conserved in 86 sequences, although only a short (ca. 87 bp) region located immediately upstream of cpsA was strictly conserved in all the sequences analyzed. An exhaustive search for possible operator sequences was done. Interestingly, although the promoter region of serotype 3 isolates completely differs from that of other serotypes, most of the proteins proposed to regulate transcription in serotype 3 pneumococci were also predicted to function as possible regulators in non-serotype 3 S. pneumoniae isolates.
| S-EPMC2695774 | biostudies-literature
Project description:We investigated the genetic structure of 99 isolates of serotype 23F Streptococcus pneumoniae from children with acute respiratory infections collected over two periods from 1997 to 2006, and 2010. All isolates were susceptible to vancomycin and amoxicillin-clavulanic acid; 97 were resistant to erythromycin, 95 of which carried the ermB gene and two carried both mefA/E and ermB genes. Multidrug resistance to three or more classes of antibiotics was exhibited by 90 isolates. Sequence types ST342 and ST81 were the most frequent in 1997-2006 and 2010, respectively. All CC81 isolates were non-susceptible to β-lactam antibiotics and had higher minimum inhibitory concentration values for penicillin than other clone complexes and sequence types. The increased β-lactam antibiotic resistance may have resulted from the replacement of multidrug-resistant clones related to ST81. Long-term studies on S. pneumoniae serotype 23F, especially the ST81 clone, should be conducted to better understand the epidemiological picture of this pathogen in China.
| S-EPMC9155283 | biostudies-literature
Project description:Combinatorial cloning and expression library analysis were used to isolate human antibody Fab fragments specific for the capsular polysaccharide of Streptococcus pneumoniae serotype 23F. Thirty 23F-specific Fabs were isolated from seven vaccinated donors, and the sequences of the heavy (H)- and light (L)-chain variable regions were determined. All individuals utilized either the Vkappa A23 L chain, the Vkappa L6 L chain, or both chains in forming the 23F-specific combining site. Vkappa A23 L chains paired primarily with VH3-23 H chains. Vkappa L6 L chains were more promiscuous in heavy-chain usage between individuals. Both H and L chains were mutated, primarily in the complementarity-determining regions, compared to their closest germ line counterpart, suggesting a recall response that has undergone affinity maturation. H-chain isotypes were reflective of those found in the serum. Shared somatic modifications demonstrated that immunoglobulin G2 (IgG2) and IgA antibodies arose from the same somatically matured B cell. Our results indicate that the response to the serotype 23F pneumococcal capsular polysaccharide is oligoclonal within the individual, with one or two paratope families accounting for the majority of expressed antibody. We also determined that, in spite of the combinatorial diversity available to the immune system, the 23F-specific response is highly restricted at the population level, with the same two L-chain-determined paratope families recurring in all individuals. Lastly, analysis of the isolated Fabs indicate all have undergone extensive somatic mutation, as well as class switch, maturational events that presumably require the participation of T cells.
| S-EPMC128163 | biostudies-literature
Project description:The primary mechanism by which pneumococcal capsular polysaccharide-based vaccines are believed to mediate protection is by induction of serotype-specific opsonic antibodies that facilitate bacterial killing by phagocytes (opsonophagocytosis). However, antibodies that are protective against experimental pneumococcal pneumonia in mice but do not promote opsonophagocytic killing in vitro have also been identified 1-3. Such non-opsonic antibodies are associated with bacterial clearance in vivo, but the mechanism by which this occurs is unknown. In this letter, we demonstrate that a protective, non-opsonic serotype 3 pneumococcal capsular polysaccharide-specific monoclonal antibody (MAb) enhances quorum sensing, which results in competence induction and fratricide of serotype 3 pneumococcus. Gene expression profile analysis revealed that the MAb together with the pneumococcal autoinducer, competence stimulating peptide 2 (CSP2), augments differential expression of competence (com) related bacteriocin-like peptide (blp) genes that are known to be involved in pneumococcal fratricide. Taken together, these findings reveal a previously unsuspected mechanism of antibody action, namely, enhancement of quorum sensing and bacterial fratricide. Given that this activity does not require phagocytes, antibodies that function accordingly may hold promise as adjuncts to current vaccines or as desired products of next generation pneumococcal vaccines.
2011-03-01 | GSE27258 | GEO
Project description:UnlabelledThe use of pneumococcal capsular polysaccharide (PPS)-based vaccines has resulted in a substantial reduction in invasive pneumococcal disease. However, much remains to be learned about vaccine-mediated immunity, as seven-valent PPS-protein conjugate vaccine use in children has been associated with nonvaccine serotype replacement and 23-valent vaccine use in adults has not prevented pneumococcal pneumonia. In this report, we demonstrate that certain PPS-specific monoclonal antibodies (MAbs) enhance the transformation frequency of two different Streptococcus pneumoniae serotypes. This phenomenon was mediated by PPS-specific MAbs that agglutinate but do not promote opsonic effector cell killing of the homologous serotype in vitro. Compared to the autoinducer, competence-stimulating peptide (CSP) alone, transcriptional profiling of pneumococcal gene expression after incubation with CSP and one such MAb to the PPS of serotype 3 revealed changes in the expression of competence (com)-related and bacteriocin-like peptide (blp) genes involved in pneumococcal quorum sensing. This MAb was also found to induce a nearly 2-fold increase in CSP2-mediated bacterial killing or fratricide. These observations reveal a novel, direct effect of PPS-binding MAbs on pneumococcal biology that has important implications for antibody immunity to pneumococcus in the pneumococcal vaccine era. Taken together, our data suggest heretofore unsuspected mechanisms by which PPS-specific antibodies could affect genetic exchange and bacterial viability in the absence of host cells.ImportanceCurrent thought holds that pneumococcal capsular polysaccharide (PPS)-binding antibodies protect against pneumococcus by inducing effector cell opsonic killing of the homologous serotype. While such antibodies are an important part of how pneumococcal vaccines protect against pneumococcal disease, PPS-specific antibodies that do not exhibit this activity but are highly protective against pneumococcus in mice have been identified. This article examines the effect of nonopsonic PPS-specific monoclonal antibodies (MAbs) on the biology of Streptococcus pneumoniae. The results showed that in the presence of a competence-stimulating peptide (CSP), such MAbs increase the frequency of pneumococcal transformation. Further studies with one such MAb showed that it altered the expression of genes involved in quorum sensing and increased competence-induced killing or fratricide. These findings reveal a novel, previously unsuspected mechanism by which certain PPS-specific antibodies exert a direct effect on pneumococcal biology that has broad implications for bacterial clearance, genetic exchange, and antibody immunity to pneumococcus.
| S-EPMC3171983 | biostudies-literature
Project description:The primary mechanism by which pneumococcal capsular polysaccharide-based vaccines are believed to mediate protection is by induction of serotype-specific opsonic antibodies that facilitate bacterial killing by phagocytes (opsonophagocytosis). However, antibodies that are protective against experimental pneumococcal pneumonia in mice but do not promote opsonophagocytic killing in vitro have also been identified 1-3. Such non-opsonic antibodies are associated with bacterial clearance in vivo, but the mechanism by which this occurs is unknown. In this letter, we demonstrate that a protective, non-opsonic serotype 3 pneumococcal capsular polysaccharide-specific monoclonal antibody (MAb) enhances quorum sensing, which results in competence induction and fratricide of serotype 3 pneumococcus. Gene expression profile analysis revealed that the MAb together with the pneumococcal autoinducer, competence stimulating peptide 2 (CSP2), augments differential expression of competence (com) related bacteriocin-like peptide (blp) genes that are known to be involved in pneumococcal fratricide. Taken together, these findings reveal a previously unsuspected mechanism of antibody action, namely, enhancement of quorum sensing and bacterial fratricide. Given that this activity does not require phagocytes, antibodies that function accordingly may hold promise as adjuncts to current vaccines or as desired products of next generation pneumococcal vaccines. 6 samples
2011-03-01 | E-GEOD-27258 | biostudies-arrayexpress
Project description:As part of large on-going vaccine impact studies in Fiji and Mongolia, we identified 25/2750 (0.9%) of nasopharyngeal swabs by microarray that were positive for Streptococcus pneumoniae contained pneumococci with a divergent 33F capsular polysaccharide locus (designated '33F-1'). We investigated the 33F-1 capsular polysaccharide locus to better understand the genetic variation and its potential impact on serotyping results. Whole genome sequencing was conducted on ten 33F-1 pneumococcal isolates. Initially, sequence reads were used for molecular serotyping by PneumoCaT. Phenotypic typing of 33F-1 isolates was then performed using the Quellung reaction and latex agglutination. Genome assemblies were used in phylogenetic analyses of each gene in the capsular locus to investigate genetic divergence. All ten pneumococcal isolates with the 33F-1 cps locus typed as 33F by Quellung and latex agglutination. Unlike the reference 33F capsule locus sequence, DNA microarray and PneumoCaT analyses found that 33F-1 pneumococci lack the wcjE gene, and instead contain wcyO with a frameshift mutation. Phylogenetic analyses found the wzg, wzh, wzd, wze, wchA, wciG and glf genes in the 33F-1 cps locus had higher DNA sequence similarity to homologues from other serotypes than to the 33F reference sequence. We have discovered a novel genetic variant of serotype 33F, which lacks wcjE and contains a wcyO pseudogene. This finding adds to the understanding of molecular epidemiology of pneumococcal serotype diversity, which is poorly understood in low and middle-income countries.
| S-EPMC6218050 | biostudies-literature