scholarly journals Identification and Characterization of thecps Locus of Streptococcus suis Serotype 2: the Capsule Protects against Phagocytosis and Is an Important Virulence Factor

1999 ◽  
Vol 67 (4) ◽  
pp. 1750-1756 ◽  
Author(s):  
Hilde E. Smith ◽  
Marloes Damman ◽  
Joeke van der Velde ◽  
Frans Wagenaar ◽  
Henk J. Wisselink ◽  
...  
Keyword(s):  
Insertional Mutagenesis ◽  
Capsular Polysaccharide ◽  
Streptococcus Suis ◽  
Open Reading Frames ◽  
Transcriptional Unit ◽  
Polysaccharide Biosynthesis ◽  
Capsule Production ◽  
Important Virulence Factor ◽  
Isogenic Mutants

ABSTRACT To study the role of the capsule of Streptococcus suisserotype 2 in virulence, we generated two isogenic mutants disturbed in capsule production. For that purpose, we first cloned and characterized a major part of the capsular polysaccharide biosynthesis (cps) locus of S. suis serotype 2. Based on the established sequence, 14 open reading frames (ORFs), designated Orf2Z, Orf2Y, Orf2X, and Cps2A to Cps2K, were identified. Twelve ORFs belonged to a single transcriptional unit. The gene products of 11 of these ORFs showed similarity to proteins involved in polysaccharide biosynthesis of other gram-positive microorganisms. Nonencapsulated isogenic mutants were generated in the cps2B and cps2EF genes by insertional mutagenesis. In contrast to the wild-type S. suis serotype 2 strain, the nonencapsulated strains were highly sensitive to ingestion by porcine alveolar lung macrophages in vitro. More importantly, the nonencapsulated mutant strains were completely avirulent in young germfree pigs after intranasal inoculation. These observations indicate that the capsule of S. suis serotype 2 plays an essential role in the pathogenesis of S. suisserotype 2 infections.

scholarly journals Overexpression of UDP-glucose dehydrogenase in Escherichia coli results in decreased biosynthesis of K5 polysaccharide

2003 ◽  
Vol 374 (3) ◽  
pp. 767-772 ◽  
Author(s):  
Elisabet ROMAN ◽  
Ian ROBERTS ◽  
Kerstin LIDHOLT ◽  
Marion KUSCHE-GULLBERG
Keyword(s):  
Escherichia Coli ◽  
Capsular Polysaccharide ◽  
Glucose Dehydrogenase ◽  
Fold Increase ◽  
Extra Copy ◽  
Polysaccharide Biosynthesis ◽  
Polysaccharide Production ◽  
Significant Difference ◽  
K5 Polysaccharide

The Escherichia coli K5 capsular polysaccharide (glycosaminoglycan) chains are composed of the repeated disaccharide structure: -GlcAβ1,4-GlcNAcα1,4-(where GlcA is glucuronic acid and GlcNAc is N-acetyl-d-glucosamine). The GlcA, present in most glycosaminoglycans, is donated from UDP-GlcA, which, in turn, is generated from UDP-glucose by the enzyme UDP-glucose dehydrogenase (UDPGDH). The formation of UDP-GlcA is critical for the biosynthesis of glycosaminoglycans. To investigate the role of UDPGDH in glycosaminoglycan biosynthesis, we used K5 polysaccharide biosynthesis as a model. E. coli was transformed with the complete gene cluster for K5 polysaccharide production. Additional transformation with an extra copy of UDPGDH resulted in an approx. 15-fold increase in the in vitro UDPGDH enzyme activity compared with the strain lacking extra UDPGDH. UDP-GlcA levels were increased 3-fold in overexpressing strains. However, metabolic labelling with [14C]glucose showed, unexpectedly, that overexpression of UDPGDH lead to decreased formation of K5 polysaccharide. No significant difference in the K5 polysaccharide chain length was observed between control and overexpressing strains, indicating that the decrease in K5-polysaccharide production most probably was due to synthesis of fewer chains. Our results suggest that K5-polysaccharide biosynthesis is strictly regulated such that increasing the amount of available UDP-GlcA results in diminished K5-polysaccharide production.

scholarly journals USA300 and USA500 Clonal Lineages of Staphylococcus aureus Do Not Produce a Capsular Polysaccharide Due to Conserved Mutations in the cap5 Locus

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Xue Li ◽  
Md Tauqeer Alam ◽  
Timothy D. Read ◽  
Julia Sieth ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
The United States ◽  
Whole Genome Sequence ◽  
Content Type ◽  
Capsule Production ◽  
Usa300 Strain

ABSTRACTThe surface capsular polysaccharide (CP) is a virulence factor that has been used as an antigen in several successful vaccines against bacterial pathogens. A vaccine has not yet been licensed againstStaphylococcus aureus, although two multicomponent vaccines that contain CP antigens are in clinical trials. In this study, we evaluated CP production in USA300 methicillin-resistantS. aureus(MRSA) isolates that have become the predominant community-associated MRSA clones in the United States. We found that all 167 USA300 MRSA and 50 USA300 methicillin-susceptibleS. aureus(MSSA) isolates were CP negative (CP−). Moreover, all 16 USA500 isolates, which have been postulated to be the progenitor lineage of USA300, were also CP−. Whole-genome sequence analysis of 146 CP−USA300 MRSA isolates revealed they all carry acap5locus with 4 conserved mutations compared with strain Newman. Genetic complementation experiments revealed that three of these mutations (in thecap5promoter,cap5Dnucleotide 994, andcap5Enucleotide 223) ablated CP production in USA300 and that Cap5E75 Asp, located in the coenzyme-binding domain, is essential for capsule production. All but three USA300 MSSA isolates had the same fourcap5mutations found in USA300 MRSA isolates. Most isolates with a USA500 pulsotype carried three of these four USA300-specific mutations, suggesting the fourth mutation occurred in the USA300 lineage. Phylogenetic analysis of thecaploci of our USA300 isolates as well as publicly available genomes from 41 other sequence types revealed that the USA300-specificcap5mutations arose sequentially inS. aureusin a common ancestor of USA300 and USA500 isolates.IMPORTANCEThe USA300 MRSA clone emerged as a community-associated pathogen in the United States nearly 20 years ago. Since then, it has rapidly disseminated and now causes health care-associated infections. This study shows that the CP-negative (CP−) phenotype has persisted among USA300 isolates and is a universal and characteristic trait of this highly successful MRSA lineage. It is important to note that a vaccine consisting solely of CP antigens would not likely demonstrate high efficacy in the U.S. population, where about half of MRSA isolates comprise USA300. Moreover, conversion of a USA300 strain to a CP-positive (CP+) phenotype is unlikelyin vivoorin vitrosince it would require the reversion of 3 mutations. We have also established that USA300 MSSA isolates and USA500 isolates are CP−and provide new insight into the evolution of the USA300 and USA500 lineages.

scholarly journals Orientations of the Bacteroides fragilis Capsular Polysaccharide Biosynthesis Locus Promoters during Symbiosis and Infection

2010 ◽  
Vol 192 (21) ◽  
pp. 5832-5836 ◽  
Author(s):  
Erin B. Troy ◽  
Vincent J. Carey ◽  
Dennis L. Kasper ◽  
Laurie E. Comstock
Keyword(s):  
Capsular Polysaccharide ◽  
Bacteroides Fragilis ◽  
Polysaccharide Biosynthesis

ABSTRACT Orientations of the seven invertible polysaccharide biosynthesis locus promoters of B acteroides fragilis were determined from bacteria grown in vitro, from feces of monoassociated and complex colonized mice, and from B. fragilis-induced murine abscesses. Bacteria grown in vivo have greater variability in orientation of polysaccharide locus promoters than culture-grown organisms.

scholarly journals Characterization of Two Plasmid-borne lpsβ Loci of Rhizobium etli Required for Lipopolysaccharide Synthesis and for Optimal Interaction with Plants

1997 ◽  
Vol 10 (7) ◽  
pp. 891-902 ◽  
Author(s):  
Alejandro García-de los Santos ◽  
Susana Brom
Keyword(s):  
Amino Acid ◽  
Dna Sequences ◽  
Open Reading Frames ◽  
Transcriptional Unit ◽  
Rhizobium Etli ◽  
Polysaccharide Biosynthesis ◽  
Strong Homology ◽  
Surface Polysaccharide ◽  
Functional Features

In Rhizobium etli CFN42, both the symbiotic plasmid (pd) and plasmid b (pb) are required for effective bean nodulation. This is due to the presence on pb of a region (lpsβ) involved in lipopolysaccharide (LPS) biosynthesis. We report here the genetic array and functional features of this plasmid-borne region. The sequence analysis of a 3,595-bp fragment revealed the presence of a transcriptional unit integrated by two open reading frames (lpsβ1 and lpsβ2) essential for LPS biosynthesis and symbiosis. The lpsβ1 encodes a putative 193 amino acid polypeptide that shows strong homology with glucosyl-1P and galactosyl-1P transferases. The deduced amino acid sequence of the protein encoded by lpsβ2 was very similar to that of proteins involved in surface polysaccharide biosynthesis, such as Pseudomonas aeruginosa WpbM, Bordetella pertussis BplL, and Yersinia enterocolitica TrsG. DNA sequences homologous to lpsβ1 and lpsβ2 of R. etli CFN42 were consistently found in functionally equivalent plasmids of R. etli, R. leguminosarum bv. viciae, and R. leguminosarum bv. trifolii strains, but not in R. meliloti, R. loti, R. tropici, R. fredii, Bradyrhizobium, Azorhizobium, and Agrobacterium tumefaciens. Even though Rhizobium and Agrobacterium do not share lpsβ sequences, their presence is required for crown-gall tumor induction by R. etli transconjugants carrying the Ti plasmid.

scholarly journals Effective antibacterial and anti-hemolysin activity of ellipticine hydrochloride against Streptococcus suis in mouse model

2021 ◽  
Author(s):  
Chenchen Wang ◽  
Hao Lu ◽  
Manli Liu ◽  
Gaoyan Wang ◽  
Xiaodan Li ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Hemolytic Activity ◽  
Bacterial Resistance ◽  
Bacterial Load ◽  
Streptococcus Suis ◽  
Resistant Bacteria ◽  
Inappropriate Use ◽  
Important Virulence Factor

Streptococcal toxic shock-like syndrome (STSLS) caused by the epidemic strain of Streptococcus suis leads to severe inflammation and high mortality. The life and health of humans and animals are also threatened by the increasingly severe antimicrobial resistance in Streptococcus suis (S. suis). To discover novel strategies for the treatment of S. suis is an urgent need. Suilysin (SLY) is considered to be an important virulence factor in the pathogenesis of S. suis. In this study, ellipticine hydrochloride (EH) was firstly reported as a compound to antagonize the hemolytic activity of SLY. In vitro, EH was found to effectively inhibit SLY-mediated hemolytic activity. Furthermore, EH and SLY had a strong affinity, thereby directly binding to SLY to interfere the hemolytic activity. Meanwhile, it was worth noting that EH was also found to have a significant antibacterial activity. In vivo, compared with traditional ampicillin, EH could not only significantly improve the survival rate of mice infected with S. suis 2 strain Sc19, but also relieve lung pathological damage. Furthermore, EH effectively decreased the levels of inflammatory cytokines (IL-6, TNF-α) and blood biochemistry (ALT, AST, CK) in Sc19-infected mice. Additionally, EH markedly reduced the bacterial load of tissues in Sc19-infected mice. In conclusion, our findings suggest that EH can be a potential compound for treating S. suis infection in view of its antibacterial and anti-hemolysin activity. Importance In recent years, the inappropriate use of antibiotics unnecessarily causes the continuous emergence of resistant bacteria. The antimicrobial resistance of Streptococcus suis (S. suis) becomes also an increasingly serious problem. Targeting virulence can reduce the selective pressure of bacteria on antibiotics, thereby alleviating the development of bacterial resistance to a certain extent. Meanwhile, the excessive inflammatory response caused by S. suis infection is considered the primary cause of acute death. Here, we found that ellipticine hydrochloride (EH) exhibited effective antibacterial and anti-hemolysin activity against S. suis in vitro. In vivo, compared with ampicillin, EH had a significant protective effect on S. suis 2 strain Sc19-infected mice. Our results indicated that EH with dual antibacterial and antivirulence effects will contribute to medicating S. suis infections and alleviating the antimicrobial resistance of S. suis to a certain extent. More importantly, EH may develop into a promising drug for the treatment of acute death caused by excessive inflammation.

scholarly journals Carbon source regulates polysaccharide capsule biosynthesis in Streptococcus pneumoniae

2019 ◽  
Vol 294 (46) ◽  
pp. 17224-17238 ◽  
Author(s):  
Lukas J. Troxler ◽  
Joel P. Werren ◽  
Thierry O. Schaffner ◽  
Nadezda Mostacci ◽  
Peter Vermathen ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Carbon Source ◽  
Capsular Polysaccharide ◽  
Carbon Sources ◽  
Cell Extract ◽  
Therapeutic Approaches ◽  
Capsule Production ◽  
Important Virulence Factor ◽  
Capsule Thickness ◽  
Whole Cell Extract

The exopolysaccharide capsule of Streptococcus pneumoniae is an important virulence factor, but the mechanisms that regulate capsule thickness are not fully understood. Here, we investigated the effects of various exogenously supplied carbohydrates on capsule production and gene expression in several pneumococcal serotypes. Microscopy analyses indicated a near absence of the capsular polysaccharide (CPS) when S. pneumoniae was grown on fructose. Moreover, serotype 7F pneumococci produced much less CPS than strains of other serotypes (6B, 6C, 9V, 15, and 23F) when grown on glucose or sucrose. RNA-sequencing revealed carbon source-dependent regulation of distinct genes of WT strains and capsule-switch mutants of serotypes 6B and 7F, but could not explain the mechanism of capsule thickness regulation. In contrast, 31P NMR of whole-cell extract from capsule-knockout strains (Δcps) clearly revealed the accumulation or absence of capsule precursor metabolites when cells were grown on glucose or fructose, respectively. This finding suggests that fructose uptake mainly results in intracellular fructose 1-phosphate, which is not converted to CPS precursors. In addition, serotype 7F strains accumulated more precursors than did 6B strains, indicating less efficient conversion of precursor metabolites into the CPS in 7F, in line with its thinner capsule. Finally, isotopologue sucrose labeling and NMR analyses revealed that the uptake of the labeled fructose subunit into the capsule is <10% that of glucose. Our findings on the effects of carbon sources on CPS production in different S. pneumoniae serotypes may contribute to a better understanding of pneumococcal diseases and could inform future therapeutic approaches.

scholarly journals Staphylococcus aureus Strains That Express Serotype 5 or Serotype 8 Capsular Polysaccharides Differ in Virulence

2005 ◽  
Vol 73 (6) ◽  
pp. 3502-3511 ◽  
Author(s):  
Andrew Watts ◽  
Danbing Ke ◽  
Qun Wang ◽  
Anil Pillay ◽  
Anne Nicholson-Weller ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
Biological Properties ◽  
Human Neutrophils ◽  
Mixed Inoculum ◽  
Serotype 5 ◽  
Biochemical Analyses ◽  
Isogenic Mutants

ABSTRACT Most isolates of Staphylococcus aureus produce a serotype 5 (CP5) or 8 (CP8) capsular polysaccharide. To investigate whether CP5 and CP8 differ in their biological properties, we created isogenic mutants of S. aureus Reynolds that expressed CP5, CP8, or no capsule. Biochemical analyses of CP5 and CP8 purified from the isogenic S. aureus strains were consistent with published structures. The degree of O acetylation of each polysaccharide was similar, but CP5 showed a greater degree of N acetylation. Mice challenged with the CP5+ strain showed a significantly higher bacteremia level than mice challenged with the CP8+ strain. Similarly, the CP5+ strain survived preferentially in the bloodstream and kidneys of infected mice challenged with a mixed inoculum containing both strains. The enhanced virulence of the CP5+ strain in vivo correlated with its greater resistance to in vitro killing in whole mouse blood. Likewise, in vitro opsonophagocytic killing assays with human neutrophils and sera revealed greater survival of the Reynolds (CP5) strain, even though the kinetics of opsonization by C3b and iC3b was similar for both the CP5+ and CP8+ strains. Electron micrographs demonstrated C3 molecules on the cell wall beneath the capsule layer for both serotype 5 and 8 strains. Purified CP5 and CP8 stimulated a modest oxidative burst in human neutrophils but failed to activate the alternative complement pathway. These results indicate that CP5 and CP8 differ in a number of biological properties, and these differences likely contribute to the relative virulence of serotype 5 and 8 S. aureus in vivo.

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 Characterization of the Pasteurella multocida hgbA Gene Encoding a Hemoglobin-Binding Protein

2002 ◽  
Vol 70 (11) ◽  
pp. 5955-5964 ◽  
Author(s):  
Montserrat Bosch ◽  
M. Elena Garrido ◽  
Montserrat Llagostera ◽  
Ana M. Pérez de Rozas ◽  
Ignacio Badiola ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Bacterial Pathogen ◽  
Open Reading Frames ◽  
Transcriptional Unit ◽  
Gene Encoding ◽  
Hemoglobin Binding ◽  
Reading Frames

ABSTRACT Reverse transcriptase PCR analyses have demonstrated that open reading frames (ORFs) PM0298, PM0299, and PM0300 of the animal pathogen Pasteurella multocida constitute a single transcriptional unit. By cloning and overexpression studies in Escherichia coli cells, the product of ORF PM0300 was shown to bind hemoglobin in vitro; this ORF was therefore designated hgbA. In vitro and in vivo quantitative assays demonstrated that the P. multocida hgbA mutant bound hemoglobin to the same extent as the wild-type strain, although the adsorption kinetics was slightly slower for the hgbA cells. In agreement with this, the virulence of P. multocida hgbA cells was not affected, suggesting that other functional hemoglobin receptor proteins must be present in this organism. On the other hand, P. multocida mutants defective in PM0298 and PM0299 could be isolated only when a plasmid containing an intact copy of the gene was present in the cells, suggesting that these genes are essential for the viability of this bacterial pathogen. By adapting the recombinase-based expression technology in vivo to P. multocida, we also demonstrated that the transcriptional PM0298-PM0299-hgbA unit is iron regulated and that its expression is triggered in the first 2 h following infection in a mouse model. Furthermore, hybridization experiments showed that the hgbA gene is widespread in P. multocida strains regardless of their serotype or the animal from which they were isolated.

scholarly journals Characterization of the cassette containing genes for type 3 capsular polysaccharide biosynthesis in Streptococcus pneumoniae.

1995 ◽  
Vol 181 (3) ◽  
pp. 973-983 ◽  
Author(s):  
J P Dillard ◽  
M W Vandersea ◽  
J Yother
Keyword(s):  
Streptococcus Pneumoniae ◽  
Capsular Polysaccharide ◽  
Gene Cassette ◽  
Polysaccharide Biosynthesis ◽  
Hybridization Data ◽  
Major Virulence Factor ◽  
The Right ◽  
Type 3

The capsular polysaccharide is the major virulence factor of Streptococcus pneumoniae. Previously, we identified and cloned a region from the S. pneumoniae chromosome specific for the production of type 3 capsular polysaccharide. Now, by sequencing the region and characterizing mutations genetically and in an in vitro capsule synthesis assay, we have assigned putative functions to the products of the type-specific genes. Using DNA from the right end of the region in mapping studies, we have obtained further evidence indicating that the capsule genes of each serotype are contained in a gene cassette located adjacent to this region. We have cloned the region flanking the left end of the cassette from the type 3 chromosome and have found that it is repeated in the S. pneumoniae chromosome. The DNA sequence and hybridization data suggest a model for recombination of the capsule gene cassettes that not only describes the replacement of capsule genes, but also suggests an explanation for binary capsule type formation, and the creation of novel capsule types.

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