Current Understanding on Biosynthesis of Microbial Polysaccharides

Wang, Peng George; Guo, Hongjie; Song, Jing

doi:10.2174/156802608783378873

Cited by 69 publications

(21 citation statements)

References 145 publications

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“…Remarkably, a total of 1,973 genes with predicted function were identified in the cps loci of the first 90 serotypes (10, 11). A similar Wzy/Wzx-dependent pathway is widely used in pathogenic bacteria for synthesis of cell wall polysaccharides, including lipopolysaccharides, capsular polysaccharides, extracellular polysaccharides, and glycosylation of certain surface glycoproteins (12). …”

Section: Introductionmentioning

confidence: 99%

Capsular Polysaccharide Expression in CommensalStreptococcusSpecies: Genetic and Antigenic Similarities to Streptococcus pneumoniae

Sørensen

Yao

Yang

et al. 2016

mBio

121

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Expression of a capsular polysaccharide is considered a hallmark of most invasive species of bacteria, including Streptococcus pneumoniae, in which the capsule is among the principal virulence factors and is the basis for successful vaccines. Consequently, it was previously assumed that capsule production distinguishes S. pneumoniae from closely related commensals of the mitis group streptococci. Based on antigenic and genetic analyses of 187 mitis group streptococci, including 90 recognized serotypes of S. pneumoniae, we demonstrated capsule production by the Wzy/Wzx pathway in 74% of 66 S. mitis strains and in virtually all tested strains of S. oralis (subspecies oralis, dentisani, and tigurinus) and S. infantis. Additional analyses of genomes of S. cristatus, S. parasanguinis, S. australis, S. sanguinis, S. gordonii, S. anginosus, S. intermedius, and S. constellatus revealed complete capsular biosynthesis (cps) loci in all strains tested. Truncated cps loci were detected in three strains of S. pseudopneumoniae, in 26% of S. mitis strains, and in a single S. oralis strain. The level of sequence identities of cps locus genes confirmed that the structural polymorphism of capsular polysaccharides in S. pneumoniae evolved by import of cps fragments from commensal Streptococcus species, resulting in a mosaic of genes of different origins. The demonstrated antigenic identity of at least eight of the numerous capsular polysaccharide structures expressed by commensal streptococci with recognized serotypes of S. pneumoniae raises concerns about potential misidentifications in addition to important questions concerning the consequences for vaccination and host-parasite relationships both for the commensals and for the pathogen.

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Section: Introductionmentioning

confidence: 99%

Capsular Polysaccharide Expression in CommensalStreptococcusSpecies: Genetic and Antigenic Similarities to Streptococcus pneumoniae

Sørensen

Yao

Yang

et al. 2016

mBio

121

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“…From an adhesive point of view, it is more appropriate to distinguish protective from aggregative polysaccharides. While protective polysaccharides provide a protective barrier around the cell, the aggregative polysaccharides have adhesive and/or cohesive properties that are exploited by bacteria to mediate adherence to surfaces and/or reinforce structural integrity of the biofilm (131, 132). Although protective polysaccharides could also contribute to the adhesive properties of bacterial cells, only the aggregative polysaccharides that serve as adhesins will be discussed in this section.…”

Section: Introductionmentioning

confidence: 99%

Adhesins Involved in Attachment to Abiotic Surfaces by Gram-Negative Bacteria

et al. 2015

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During the first step of biofilm formation, initial attachment is dictated by physicochemical and electrostatic interactions between the surface and the bacterial envelope. Depending upon the nature of these interactions, attachment can be transient or permanent. To achieve irreversible attachment, bacterial cells have developed a series of surface adhesins promoting specific or non-specific adhesion under various environmental conditions. This chapter will review the recent advances in our understanding of the secretion, assembly and regulation of the bacterial adhesins during biofilm formation with a particular emphasis on the fimbrial, non-fimbrial and discrete polysaccharide adhesins in Gram-negative bacteria.

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“…S. flexneri Oag biosynthesis occurs on either side of the inner membrane (IM). Initially, N-acetylglucosamine phosphate (GlcNAc-1-P) is transferred from UDP-GlcNAc by WecA to undecaprenol phosphate (Und-P) at the cytoplasmic side of the IM (5,15,16). RfbG and RfbF then add Rha residues from dTDPrhamnose (dTDP-Rha) to the GlcNAc (3,17) to form the O unit.…”

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confidence: 99%

Mutational Analysis of the Shigella flexneri O-Antigen Polymerase Wzy: Identification of Wzz-Dependent Wzy Mutants

2015

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The O-antigen (Oag) component of lipopolysaccharide (LPS) is a major virulence determinant of Shigella flexneri and is synthesized by the O-antigen polymerase, Wzy Sf . Oag chain length is regulated by chromosomally encoded Wzz Sf and pHS-2 plasmidencoded Wzz pHS2 . To identify functionally important amino acid residues in Wzy Sf , random mutagenesis was performed on the wzy Sf gene in a pWaldo-TEV-GFP plasmid, followed by screening with colicin E2. Analysis of the LPS conferred by mutated Wzy Sf proteins in the wzy Sf -deficient (⌬wzy) strain identified 4 different mutant classes, with mutations found in periplasmic loop 1 (PL1), PL2, PL3, and PL6, transmembrane region 2 (TM2), TM4, TM5, TM7, TM8, and TM9, and cytoplasmic loop 1 (CL1) and CL5. S higella flexneri lipopolysaccharide (LPS) is crucial for pathogenesis (1). LPS is located exclusively in the outer leaflet of the outer membrane (OM) and has three domains: (i) lipid A, a hydrophobic domain that anchors LPS to the OM; (ii) the core oligosaccharides, a nonrepeating oligosaccharide domain; and (iii) the O-antigen (Oag) polysaccharide, an oligosaccharide repeat domain (1, 2). The complete LPS structure with Oag chains is termed smooth LPS (S-LPS). However, the LPS structure lacking the Oag is termed rough LPS (R-LPS), and LPS with a single Oag tetrasaccharide repeat unit (RU) attached to the lipid A and core sugar is termed semirough LPS (SR-LPS) (3). S. flexneri is subdivided into various serotypes depending on the differences in the composition of the LPS Oag. So far, there are 17 known serotypes of S. flexneri (4). Except for S. flexneri serotype 6, the Oags of all the serotypes have the same polysaccharide backbone containing three L-rhamnose residues (Rha) and one N-acetylglucosamine (GlcNAc). This basic Oag structure is known as serotype Y. Addition of either glucosyl, O-acetyl, or phosphoethanolamine (PEtN) groups by various linkages to the sugars of the Y serotype tetrasaccharide repeat creates different S. flexneri serotypes (5-7). Oag is the protective antigen, as immunity to S. flexneri infection is serotype specific (8, 9). S-LPS confers resistance to complement (10) and colicins (11,12), and Y serotype Oag acts as a receptor to bacteriophage Sf6 (13).S. flexneri Oag biosynthesis occurs by the Wzy-dependent pathway. Most of the Oag biosynthesis genes (except wecA) of S. flexneri are located in the Oag biosynthesis locus between galF and his (6, 14). S. flexneri Oag biosynthesis occurs on either side of the inner membrane (IM). Initially, N-acetylglucosamine phosphate (GlcNAc-1-P) is transferred from UDP-GlcNAc by WecA to undecaprenol phosphate (Und-P) at the cytoplasmic side of the IM (5, 15, 16). RfbG and RfbF then add Rha residues from dTDPrhamnose (dTDP-Rha) to the GlcNAc (3, 17) to form the O unit. In the Wzy-dependent model of LPS assembly, the flippase protein Wzx translocates this O unit to the periplasmic side. At the periplasmic side, the O units are polymerized at the nonreducing end by the Oag polymerization protein Wzy via a block ...

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Current Understanding on Biosynthesis of Microbial Polysaccharides

Cited by 69 publications

References 145 publications

Capsular Polysaccharide Expression in CommensalStreptococcusSpecies: Genetic and Antigenic Similarities to Streptococcus pneumoniae

Capsular Polysaccharide Expression in CommensalStreptococcusSpecies: Genetic and Antigenic Similarities to Streptococcus pneumoniae

Adhesins Involved in Attachment to Abiotic Surfaces by Gram-Negative Bacteria

Mutational Analysis of the Shigella flexneri O-Antigen Polymerase Wzy: Identification of Wzz-Dependent Wzy Mutants

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