Structural Characterization of Streptococcus pneumoniae Serotype 9A Capsule Polysaccharide Reveals Role of Glycosyl 6-O-Acetyltransferase wcjE in Serotype 9V Capsule Biosynthesis and Immunogenicity

Calix, Juan J.; Saad, Jamil S.; Brady, Allison M.; Nahm, Moon H.

doi:10.1074/jbc.m112.346924

Cited by 30 publications

(31 citation statements)

References 33 publications

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“…Flow Cytometry-The flow cytometric serotyping assay was performed as described (10,21). Frozen bacteria aliquots were thawed, washed, normalized to A 630 of 0.02 in FACS buffer (PBS containing 4% fetal bovine serum (Thermo Scientific Hyclone, Logan, UT)), added to a V-bottomed ELISA plate (Nunc, Roskilde, Denmark), and incubated with a culture supernatant of a hybridoma at 1:40 final dilution.…”

Section: Methodsmentioning

confidence: 99%

Discovery of Streptococcus pneumoniae Serotype 6 Variants with Glycosyltransferases Synthesizing Two Differing Repeating Units

Oliver

Linden

Küntzel

et al. 2013

Journal of Biological Chemistry

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Background: Two atypical serogroup 6 strains have been discovered. Results: They express capsular polysaccharide with two different repeating units and share A150T mutation in WciN␣. Conclusion: This mutation shifts WciN␣ from a galactosyltransferase to a bi-specific glycosyltransferase, creating two new hybrid serotypes: 6F and 6G. Significance: Pneumococci can change capsule serotypes by point mutations and may alter their interactions with the immunity of the host.

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Section: Methodsmentioning

confidence: 99%

Discovery of Streptococcus pneumoniae Serotype 6 Variants with Glycosyltransferases Synthesizing Two Differing Repeating Units

Oliver

Linden

Küntzel

et al. 2013

Journal of Biological Chemistry

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“…Our assignment of WciG and WcjE to the two positions of O-acetylation of CPS47F (Fig. 4) was made in view of previous findings (17,19,(22)(23)(24) that associate wciG with 2-O-acetylation of wcrD-dependent Galf in CPS serotypes 20B, 33F, 33A, 33B, 33D, and 35A and wcjE with 5,6-O-acetylation of wciB-dependent Galf in CPS serotypes 20, 33A, and 35A and 3,5-O-acetylation of 47A. The synthesis of S. pneumoniae CPS serogroup 35 involves a number of genes that are considered in the present study, as well as other genes (6, 7) that have not been associated with specific steps in polysaccharide biosynthesis.…”

Section: Discussionmentioning

confidence: 78%

Chemical Structures of Streptococcus pneumoniae Capsular Polysaccharide Type 39 (CPS39), CPS47F, and CPS34 Characterized by Nuclear Magnetic Resonance Spectroscopy and Their Relation to CPS10A

Bush

Yang

Yu³

et al. 2014

J Bacteriol

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c Structural characterization of Streptococcus pneumoniae capsular polysaccharides (CPS) is a prerequisite for unraveling both antigenic and genetic relationships that exist between different serotypes. In the current study, comparative structural studies of S. pneumoniae CPS serogroup 10 (CPS10) were extended to include genetically related S. pneumoniae CPS34, CPS39, and CPS47F. High-resolution heteronuclear nuclear magnetic resonance (NMR) spectroscopy confirmed the published structure of CPS34 and, in conjunction with glycosyl composition analyses, revealed the following repeat unit structures of the other serotypes, which have not been previously characterized:Common and unique structural features of these polysaccharides, including different positions of O-acetylation, were unambiguously associated with specific genes in each corresponding cps locus. The only exception involved the gene designated wcrC, which is associated with the ␣1-2 transfer of Gal pyranoside (Galp) to ribitol-5-phosphate in the synthesis of CPS10A, CPS47F, and CPS34 but with ␣1-1 transfer of Gal to ribitol-5-phosphate in the synthesis of CPS39. The corresponding gene in the cps39 locus, although related to wcrC, more closely resembled a previously identified gene (i.e., wefM) of Streptococcus oralis that is associated with ␣1-1 transfer of Galp to ribitol-5-phosphate. These and other recent findings identify linkages from ␣-Galp to ribitol-5-phosphate and from this residue to adjacent Gal furanoside (Galf) as important sites of CPS structural and genetic diversity. Streptococcus pneumoniae capsular polysaccharides (CPS) are of interest both as virulence factors and as protective immunogens for serotype-specific prevention of invasive disease. Currently recommended CPS-based vaccines include the 23-valent pneumococcal polysaccharide vaccine for adults and the 13-valent pneumococcal conjugate vaccine for children. Monitoring the efficacy of these vaccines requires ongoing surveillance of invasive pneumococcal serotypes (1). The traditional method for serotyping these bacteria is the Neufeld-Quellung test, which detects apparent swelling of bacterial capsules in the presence of factor antisera (2). Such determinations, although reliable, require training, experience, and specialized immunological reagents and, thus, are not amenable to widespread use. Molecular methods for serotyping these bacteria have also been described and are being developed that target genes for CPS biosynthesis in large operons (cps loci) located between dexB and aliA (3, 4). Sequencing of this region in reference strains of 88 S. pneumoniae serotypes revealed 1,502 genes, each defined by a different protein homology group (5). These include 430 genes for putative glycosyltransferases, 69 for sugar/polyalcohol phosphate transferases, 78 for acetyltransferases, 90 for different polymerases (Wzy) and 88 for different flippases (Wzx) (6). The proteins encoded by some of these genes have been shown biochemically to have the predicted function (4), and a number of other...

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“…Our discovery of serotype 35D further illustrates that genetic inactivation of membranebound O-acetyltransferases is a commonly used mechanism for generating variation in capsular polysaccharides. For example, wcjE-positive and -negative pairs are known to exist in many serotypes (6,11,23), and serotype pairs 15B/15C and 18C/18B are differentiated by O-acetyltransferase functionality (6). Here, we have presented the first described serotype arising from wciG inactivation.…”

Section: Discussionmentioning

confidence: 96%

Discovery of Novel Pneumococcal Serotype 35D, a Natural WciG-Deficient Variant of Serotype 35B

2017

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Pneumococcus (Streptococcus pneumoniae) remains a significant cause of morbidity and mortality, especially among those at the extremes of age. Its capsular polysaccharide is essential for systemic virulence. Over 90 serologically distinct pneumococcal capsular polysaccharides (serotypes) are recognized, but they are unequal in prevalence. Because antibodies against the capsule are protective, polysaccharide conjugate vaccines, which are constructed against the most prevalent serotypes, have caused great reductions in pneumococcal disease caused by these serotypes. In response, however, the relative prevalences of serotypes have shifted. Certain previously rare serotypes, such as serotype 35B, are increasing in prevalence. Serotype 35B is thus a likely future vaccine candidate, but due to their previous rarity, serotype 35B strains have not been scrutinized for underlying heterogeneity. We studied putative serotype 35B clinical isolates to assess the uniformity of their serological reactions. While most isolates exhibited the accepted serology of serotype 35B, one isolate failed to bind to critical serotyping reagents. We determined that the genetic basis for this aberrant serology was the presence of inactivating mutations in the O-acetyltransferase gene wciG. Complementation studies in a wciG deletion strain verified that the mutant WciG was nonfunctional, and the serology of the mutant could be restored through complementation with a construct encoding a functional WciG. Nuclear magnetic resonance studies confirmed that the capsule of the WciG-deficient isolate lacked O-acetylation but was otherwise identical to serotype 35B. As this isolate expresses a unique serology with unique biochemistry and a stable genetic basis, we named its novel capsule serotype 35D.KEYWORDS O-acetylation, Streptococcus pneumoniae, capsular polysaccharide, serogroup 35, serotype 35B, serotype 35D S treptococcus pneumoniae (pneumococcus) is an important human pathogen that can express many different polysaccharide capsules that protect the organism from opsonophagocytic killing (1). As antibodies to the capsule are protective, currently available vaccines against pneumococcus are designed to elicit antibodies to the capsule and have been highly successful in reducing the incidence of invasive pneumococcal disease (IPD). A pneumococcal polysaccharide-protein conjugate vaccine (PCV) with polysaccharide from the seven most commonly observed serotypes (PCV7) was introduced in the United States in 2000 and reduced the incidence of IPD in children younger than 5 by over 75% (2); the updated 13-valent PCV (PCV13) has reduced the incidence of IPD by an additional 64% in this age group in the United States (3). However, the protection by these vaccines is serotype specific, and their widespread implementation has brought shifts in the serotypes found in both nasopharyngeal carriage and IPD (see, e.g., reference 4).

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Structural Characterization of Streptococcus pneumoniae Serotype 9A Capsule Polysaccharide Reveals Role of Glycosyl 6-O-Acetyltransferase wcjE in Serotype 9V Capsule Biosynthesis and Immunogenicity

Cited by 30 publications

References 33 publications

Discovery of Streptococcus pneumoniae Serotype 6 Variants with Glycosyltransferases Synthesizing Two Differing Repeating Units

Discovery of Streptococcus pneumoniae Serotype 6 Variants with Glycosyltransferases Synthesizing Two Differing Repeating Units

Chemical Structures of Streptococcus pneumoniae Capsular Polysaccharide Type 39 (CPS39), CPS47F, and CPS34 Characterized by Nuclear Magnetic Resonance Spectroscopy and Their Relation to CPS10A

Discovery of Novel Pneumococcal Serotype 35D, a Natural WciG-Deficient Variant of Serotype 35B

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