Confirmation of the D configuration of the 2-substituted arabinitol 1-phosphate residue in the capsular polysaccharide from Streptococcus pneumoniae Type 17F

Ultrastructural, Energy-Dispersive X-ray Spectroscopy, Chemical Study and LC-DAD-QToF Chemical Characterization of Cetraria islandica (L.) Ach

The lichen Cetraria islandica (L.) Ach. has been used in traditional and modern medicines for its many biological properties such as immunological, immunomodulating, antioxidant, antimicrobial, and anti-inflammatory activities. This species is gaining popularity in the market, with interest from many industries for selling as medicines, dietary supplements, and daily herbal drinks. This study profiled the morpho-anatomical features by light, fluorescence, and scanning electron microscopy; conducted an elemental analysis using energy-dispersive X-ray spectroscopy; and phytochemical analysis was performed using high-resolution mass spectrometry combined with a liquid chromatography system (LC-DAD-QToF) of C. islandica. In total, 37 compounds were identified and characterized based on comparisons with the literature data, retention times, and their mass fragmentation mechanism/s. The identified compounds were classified under five different classes, i.e., depsidones, depsides, dibenzofurans, aliphatic acids, and others that contain simple organic acids in majority. Two major compounds (fumaroprotocetraric acid and cetraric acid) were identified in the aqueous ethanolic and ethanolic extracts of C. islandica lichen. This detailed morpho-anatomical, EDS spectroscopy, and the developed LC-DAD-QToF approach for C. islandica will be important for correct species identification and can serve as a useful tool for taxonomical validation and chemical characterization. Additionally, chemical study of the extract of C. islandica led to isolation and structural elucidation of nine compounds, namely cetraric acid (1), 9'-(O-methyl)protocetraric acid (2), usnic acid (3), ergosterol peroxide (4), oleic acid (5), palmitic acid (6), stearic acid (7), sucrose (8), and arabinitol (9).

Bacterial surface capsular polysaccharides from Streptococcus pneumoniae: A systematic review on structures, syntheses, and glycoconjugate vaccines

The polysaccharide capsule of Streptococcus pneumoniae constitutes the outermost surface structure of the organism and plays a critical role in virulence. The capsule is the target of current pneumococcal vaccines and glycoconjugates and has important medical and industrial applications. Widespread use of these vaccines is driving changes in serotype prevalence in disease. A massive array of sugars and glycosidic linkages experienced with complete diversity of potential polysaccharide structures. However, it is impossible to collect a sufficient quantity of glycan antigens for the preparation of CPS-based glycoconjugate vaccines from natural sources with high purity and for thorough biological evaluation. So nowadays, the development of a chemical synthetic strategy and their conjugation with a carrier protein to form synthetic glycoconjugate vaccines has been used to gain access on a large scale. This review provides a comprehensive summary of structures, synthesis as well as recent development of synthetic glycoconjugate vaccines, which will support research and may benefit the glycochemical and medical sciences.

Pneumococcal Capsules and Their Types: Past, Present, and Future

Streptococcus pneumoniae (the pneumococcus) is an important human pathogen. Its virulence is largely due to its polysaccharide capsule, which shields it from the host immune system, and because of this, the capsule has been extensively studied. Studies of the capsule led to the identification of DNA as the genetic material, identification of many different capsular serotypes, and identification of the serotype-specific nature of protection by adaptive immunity. Recent studies have led to the determination of capsular polysaccharide structures for many serotypes using advanced analytical technologies, complete elucidation of genetic basis for the capsular types, and the development of highly effective pneumococcal conjugate vaccines. Conjugate vaccine use has altered the serotype distribution by either serotype replacement or switching, and this has increased the need to serotype pneumococci. Due to great advances in molecular technologies and our understanding of the pneumococcal genome, molecular approaches have become powerful tools to predict pneumococcal serotypes. In addition, more-precise and -efficient serotyping methods that directly detect polysaccharide structures are emerging. These improvements in our capabilities will greatly enhance future investigations of pneumococcal epidemiology and diseases and the biology of colonization and innate immunity to pneumococcal capsules.

Biochemical characterization of the CDP-D-arabinitol biosynthetic pathway in Streptococcus pneumoniae 17F

Streptococcus pneumoniae is a major human pathogen associated with many diseases worldwide. Capsular polysaccharides (CPSs) are the major virulence factor. The biosynthetic pathway of D-arabinitol, which is present in the CPSs of several S. pneumoniae serotypes, has never been identified. In this study, the genes abpA (previously known as abp1) and abpB (previously known as abp2), which have previously been reported to be responsible for nucleoside diphosphate (NDP)-D-arabinitol (the nucleotide-activated form of D-arabinitol) synthesis, were cloned. The enzyme products were overexpressed, purified, and analyzed for their respective activities. Novel products produced by AbpA- and AbpB-catalyzing reactions were detected by capillary electrophoresis, and the structures of the products were elucidated using electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. As a result, abpA was identified to be a D-xylulose-5-phosphate cytidylyltransferase-encoding gene, responsible for the transfer of CTP to D-xylulose-5-phosphate (D-Xlu-5-P) to form CDP-D-xylulose, and abpB was characterized to be a CDP-D-xylulose reductase-encoding gene, responsible for the conversion of CDP-D-xylulose to CDP-D-arabinitol as the final product. The kinetic parameters of AbpA for the substrates D-Xlu-5-P and CTP and those of AbpB for the substrate CDP-D-xylulose and the cofactors NADH or NADPH were measured, and the effects of temperature, pH, and cations on the two enzymes were analyzed. This study confirmed the involvement of the genes abpA and abpB and their products in the biosynthetic pathway of CDP-D-arabinitol.

Bacterial capsular antigens. Structural patterns of capsular antigens

Structural patterns of bacterial capsular antigens including capsular polysaccharides and exoglycans are given in this review. In addition, the immunological activity of capsular antigens and their role in type specificity of bacteria are discussed.

A mannitol teichoic acid containing rhamnose and pyruvic acid acetal from the cell wall of Brevibacterium permense VKM Ac-2280

The cell wall of Brevibacterium permense VKM Ac-2280 contains two teichoic acids. The major polymer represents a 1,6-poly(mannitol phosphate) substituted wirh either L-rhamnose (approximately 70%, unit A) or (S)-acetal of pyruvic acid (approximately 30%, unit B) with the overall chain length approximately 10 mannitol phosphate units. [carbohydrate structure: see text] The other polymer is an unsubstituted 1,3-poly(glycerol phosphate). The structures of the polymers were established using chemical degradations and NMR spectroscopy. The data obtained may be helpful in determination of the species-specific status of newly isolated Brevibacterium strains.