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  • 1
    Electronic Resource
    Electronic Resource
    Presence of a small plasmid in clinical isolates of Streptococcus pneumoniae (1989)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 65 (1989), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract We have detected the presence of a small (2.95 kb) plasmid in a clinical isolate of Streptococcus pneumoniae. A restriction map was constructed for this plasmid and for pDP1 (the only previously reported pneumococcal plasmid); no apparent differences were observed and the two plasmids hybridized strongly to each other. Portions of pDP1 were then cloned into Escherichia coli K-12, using the vector pUC19, and the pneumococcal DNA insert was used as a probe to screen 500 clinical isolates of S. pneumoniae for pDP1 sequences. The plasmid was detected in a total of 8 isolates. These were of various serotypes and no correlation could be found between the presence of the plasmid and the geographical location from which it came, the type of infection, or with resistence to antibacterial drugs. Although no function has yet been assigned to pDP1, it may form the basis of a useful vector for cloning in S. pneumoniae, as it contains at least seven unique restriction sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1989.tb03673.x
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  • 2
    Electronic Resource
    Electronic Resource
    Expression, purification and preliminary X-ray crystallographic analysis of PsaA, a putative metal-transporter protein of Streptococcus pneumoniae (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1464-1466 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The putative metal-transporter protein PsaA of Streptococcus pneumoniae is of potential interest both as a vaccine and also as a drug target. The overexpression of the protein in E. coli, and its subsequent purification and crystallization are described. The crystals are rectangular rods and diffract to beyond 2.7 Å resolution. The crystal space group is P212121 with unit-cell dimensions a = 59.9, b = 66.5 and c = 69.9 Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444998005812
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  • 3
    Electronic Resource
    Electronic Resource
    Recombinational exchanges at the capsular polysaccharide biosynthetic locus lead to frequent serotype changes among natural isolates of Streptococcus pneumoniae (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Serotype 19F variants of the major Spanish multiresistant serotype 23F clone of Streptococcus pneumoniae have been proposed to have arisen by recombinational exchanges at the capsular biosynthetic locus. Members of the Spanish multiresistant serotype 23F clone and the serotype 19F variants were confirmed to be essentially identical in overall genotype, as they were indistinguishable by REP-PCR, and had identical sequences at three polymorphic housekeeping genes. Eight serotype 19F variants were studied and all had large recombinational replacements at the capsular biosynthetic locus. In all cases, one of the recombinational cross-over points appeared to be upstream of dexBwhich flanks one end of the capsular locus, and in six of the variants the other cross-over point was downstream of aliA, which flanks the other end of the locus. In two strains a recombinational cross-over point between the introduced serotype 19F capsular region and that of the Spanish serotype 23F clone could be clearly identified, within cpsN in one strain and within cpsM in the other. The differences in the recombinational junctions and sequence polymorphisms within the introduced capsular genes, suggested that the eight serotype 19F variants emerged on at least four separate occasions. Changes in capsular type by recombination may therefore be relatively frequent in pneumococci and this has implications for the long-term efficacy of conjugate pneumococcal vaccines that will protect against only a limited number of serotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00658.x
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of the locus encoding the Streptococcus pneumoniae type 19F capsular polysaccharide biosynthetic pathway (1997)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have previously reported the nucleotide sequence of the first six genes of the Streptococcuspneumoniae type 19F capsular polysaccharide biosynthesis locus (cps19f). In this study we used plasmid insertion/rescue and inverse polymerase chain reaction (PCR) to clone an additional 10 kb downstream region containing the remainder of the cps19f locus, which was then subjected to sequence analysis. The cps19f locus is located in the S. pneumoniae chromosome between dexB and aliA, and consists of 15 open reading frames (ORFs), designated cps19fA to cps19fO, that appear to be arranged as a single transcriptional unit. Insertion-duplication mutants in seven out of the nine new ORFs have been constructed in a smooth type 19F strain, all of which resulted in a rough (non-encapsulated) phenotype, confirming that the operon is essential for capsule production. Comparison with sequence databases has allowed us to propose functions for 12 of the cps19f gene products, and a biosynthetic pathway for type 19F capsular polysaccharide. T7 expression studies confirmed that cps19fH, cps19fK, cps19fL, cps19fM and cps19fN directed the production of polypeptides of the expected size in Escherichia coli. The function of the cps19fK product was confirmed by its ability to complement a mutation in nfrC (rffE ) in E. coli, as judged by restoration of sensitivity to bacteriophage N4. Interestingly, the last four genes of the locus (cps19fL–O ) exhibit very strong homology (up to 70% amino acid identity) to a portion of the Shigella flexneri rfb gene cluster encoding biosynthesis of dTDP-rhamnose. When expressed in E. coli, cps19fL–O were capable of complementing a mutation deleting the respective Shigella flexneri homologues. Southern hybridization analysis indicated that cps19fA and cps19fB were the only cps genes found in all 16 S. pneumoniae serotypes/groups tested. The region from cps19fG to cps19fK was found only in members of serogroup 19, and, within this, cps19fI was unique to type 19F.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2551624.x
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  • 5
    Electronic Resource
    Electronic Resource
    AB 5 subtilase cytotoxin inactivates the endoplasmic reticulum chaperone BiP (2006)
    [s.l.] : Nature Publishing Group
    Nature 443 (2006), S. 548-552 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] AB5 toxins are produced by pathogenic bacteria and consist of enzymatic A subunits that corrupt essential eukaryotic cell functions, and pentameric B subunits that mediate uptake into the target cell. AB5 toxins include the Shiga, cholera and pertussis toxins and a recently ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature05124
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular analysis of the psa permease complex of Streptococcus pneumoniae (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 53 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The psaBCA locus of Streptococcus pneumoniae encodes a putative ABC Mn2+-permease complex. Downstream of the operon is psaD, which may be co-transcribed and encodes a thiol peroxidase. Previously, there has been discordance concerning the phenotypic impact of mutations in the psa locus, resolution of which has been complicated by differences in mutant construction and the possibility of polar effects. Here, we constructed unmarked, in frame deletion mutants ΔpsaB, ΔpsaC, ΔpsaA, ΔpsaD, ΔpsaBC, ΔpsaBCA and ΔpsaBCAD in S. pneumoniae D39 to examine the role of each gene within the locus in Mn2+ uptake, susceptibility to oxidative stress, virulence, nasopharyngeal colonization and chain morphology. The requirement for Mn2+ for growth and transformation was also investigated for all mutants. Inductively coupled plasma mass spectrometry (ICP-MS) analysis provided the first direct evidence that PsaBCA is indeed a Mn2+ transporter. However, this study did not substantiate previous reports that the locus plays a role in choline-binding protein pro-duction or chain morphology. We also confirmed the importance of the Psa permease in systemic virulence and resistance to superoxide and hydrogen peroxide, as well as demonstrating a role in nasopharyngeal colonization for the first time. Further evi-dence is provided to support the requirement for Mn2+ supplementation for growth and transformation of ΔpsaB, ΔpsaC, ΔpsaA, ΔpsaBC, ΔpsaBCA and ΔpsaBCAD mutants. However, transformation, as well as growth, of the ΔpsaD mutant was not dependent upon Mn2+ supplementation. We also show that, apart from sensitivity to hydrogen peroxide, the ΔpsaD mutant exhibited essentially similar phenotypes to those of the wild type. Western blot analysis with a PsaD antiserum showed that deleting any of the genes upstream of psaD did not affect its expression. However, we found that deleting psaB resulted in decreased expression of PsaA relative to that in D39, whereas deleting both psaB and psaC resulted in at least wild-type levels of PsaA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04164.x
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  • 7
    Electronic Resource
    Electronic Resource
    Penicillin tolerance in Streptococcus pneumoniae, autolysis and the Psa ATP-binding cassette (ABC) manganese permease (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 32 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01369.x
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  • 8
    Electronic Resource
    Electronic Resource
    Tyrosine phosphorylation of CpsD negatively regulates capsular polysaccharide biosynthesis in Streptococcus pneumoniae (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 35 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In Streptococcus pneumoniae, the first four genes of the capsule locus (cpsA to cpsD) are common to most serotypes. By analysis of various in-frame deletion and site-directed mutants, the function of their gene products in capsular polysaccharide (CPS) biosynthesis was investigated. We found that while CpsB, C and D are essential for encapsulation, CpsA is not. CpsC and CpsD have similarity to the amino-terminal and carboxy-terminal regions, respectively, of the autophosphorylating protein-tyrosine kinase Wzc from Escherichia coli. Alignment of CpsD with Wzc and other related proteins identified conserved Walker A and B sequence motifs and a tyrosine rich domain close to the carboxy-terminus. We have shown that CpsD is also an autophosphorylating protein-tyrosine kinase and that point mutations in cpsD affecting either the ATP-binding domain (Walker A motif) or the carboxy-terminal [YGX]4 repeat domain eliminated tyrosine phosphorylation of CpsD. We describe, for the first time, the phenotypic impact of these two mutations on polysaccharide production and show that they affect CPS production differently. Whereas a mutation in the Walker A motif resulted in loss of encapsulation, mutation of the tyrosines in the [YGX]4 repeat domain resulted in an apparent increase in encapsulation and a mucoid phenotype. These data suggest that autophosphorylation of CpsD at tyrosine attenuates its activity and reduces the level of encapsulation. Additionally, we demonstrated that CpsC is required for CpsD tyrosine phosphorylation and that CpsB influences dephosphorylation of CpsD. These results are consistent with CpsD tyrosine phosphorylation acting to negatively regulate CPS production. This has implications for the function of CpsC/CpsD homologues in both Gram-positive and Gram-negative bacteria and provides a mechanism to explain regulation of CPS production during pathogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.01808.x
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  • 9
    Electronic Resource
    Electronic Resource
    The NADH oxidase of Streptococcus pneumoniae : its involvement in competence and virulence[Part of th] (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A soluble flavoprotein that reoxidizes NADH and reduces molecular oxygen to water was purified from the facultative anaerobic human pathogen Streptococcus pneumoniae. The nucleotide sequence of nox, the gene which encodes it, has been determined and was characterized at the functional and physiological level. Several nox mutants were obtained by insertion, nonsense or missense mutation. In extracts from these strains, no NADH oxidase activity could be measured, suggesting that a single enzyme encoded by nox, having a C44 in its active site, was utilizing O2 to oxidize NADH in S. pneumoniae. The growth rate and yield of the NADH oxidase-deficient strains were not changed under aerobic or anaerobic conditions, but the efficiency of development of competence for genetic transformation during growth was markedly altered. Conditions that triggered competence induction did not affect the amount of Nox, as measured using Western blotting, indicating that nox does not belong to the competence-regulated genetic network. The decrease in competence efficiency due to the nox mutations was similar to that due to the absence of oxygen in the nox+ strain, suggesting that input of oxygen into the metabolism via NADH oxidase was important for controlling competence development throughout growth. This was not related to regulation of nox expression by O2. Interestingly, the virulence and persistence in mice of a blood isolate was attenuated by a nox insertion mutation. Global cellular responses of S. pneumoniae, such as competence for genetic exchange or virulence in a mammalian host, could thus be modulated by oxygen via the NADH oxidase activity of the bacteria, although the bacterial energetic metabolism is essentially anaerobic. The enzymatic activity of the NADH oxidase coded by nox was probably involved in transducing the external signal, corresponding to O2 availability, to the cell metabolism and physiology; thus, this enzyme may function as an oxygen sensor. This work establishes, for the first time, the role of O2 in the regulation of pneumococcal transformability and virulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01663.x
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  • 10
    Electronic Resource
    Electronic Resource
    A new biological agent for treatment of Shiga toxigenic Escherichia coli infections and dysentery in humans (2000)
    [s.l.] : Nature America Inc.
    Nature medicine 6 (2000), S. 265-270 
    Details
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Gastrointestinal disease caused by Shiga toxin-producing bacteria (such as Escherichia coli O157:H7 and Shigella dysenteriae) is often complicated by life-threatening toxin-induced systemic sequelae, including hemolytic–uremic syndrome. Such infections can now be diagnosed very early in ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/73111
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