8 research outputs found

    Positive role of cell wall anchored proteinase PrtP in adhesion of lactococci-1

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    <p><b>Copyright information:</b></p><p>Taken from "Positive role of cell wall anchored proteinase PrtP in adhesion of lactococci"</p><p>http://www.biomedcentral.com/1471-2180/7/36</p><p>BMC Microbiology 2007;7():36-36.</p><p>Published online 2 May 2007</p><p>PMCID:PMC1876236.</p><p></p

    Positive role of cell wall anchored proteinase PrtP in adhesion of lactococci-0

    No full text
    <p><b>Copyright information:</b></p><p>Taken from "Positive role of cell wall anchored proteinase PrtP in adhesion of lactococci"</p><p>http://www.biomedcentral.com/1471-2180/7/36</p><p>BMC Microbiology 2007;7():36-36.</p><p>Published online 2 May 2007</p><p>PMCID:PMC1876236.</p><p></p

    Electron microscopy imaging of NEM316 WT, <i>ΔgbcO</i> mutant, and complemented strains.

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    <p>Bacteria were harvested in mid-log phase (OD<sub>600 nm</sub> = 0.5), fixed, and prepared as described in Supporting <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002756#s3" target="_blank">Materials and Methods</a> (see <b><a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002756#ppat.1002756.s005" target="_blank">Text S1</a></b>) (<b>A</b>) Representative views of scanning electron microcopy analysis illustrating the morphological alterations (size, form, and cell division abnormalities) due to <i>gbcO</i> inactivation. (<b>B, C</b>) Transmission electron microscopy views of uranyl acetate stained thin cryosections at two magnifications (see scale bars). The presence of the pellicle (electron dense outer layer) at the surface of WT and complemented strains observed at the higher magnification is highlighted with black arrows. An open triangle depicts the equatorial ring (EqR), a zone of active peptidoglycan synthesis seen in almost all WT and complemented cells but absent in the <i>ΔgbcO</i> mutant cells.</p

    Structure of GBC and proposed scheme of GBC synthesis.

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    <p>(<b>A</b>) The multiantennary GBC is shown linked to an N-acetyl muramic (NAM) moiety, a component of PG. (<b>B</b>) The figure depicts the first steps of GBC synthesis where GbcO is proposed to catalyze the transfer of UDP-GlcNAc to a lipid phosphate carrier.</p

    Decreased growth rate and lack of tunicamycin sensitivity of <i>ΔgbcO</i> mutant.

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    <p>(<b>A</b>) Growth curves of NEM316 WT (solid squares), Δ<i>gbcO</i> mutant (circles) and Δ<i>gbcO</i>pTCVΩ<i>gbcO</i> (empty squares) strains. Cultures were performed in TH medium without antibiotics at 37°C in 96 wells plates in triplicate. Optical densities were recorded at 600 nm in a Tecan M200 apparatus with 5 sec agitation before measure. Average values of a typical experiment are presented. (<b>B</b>) Effect of various concentrations of tunicamycin on the growth rate of WT (solid squares), <i>ΔgbcO</i> (black circles) and Δ<i>gbcO</i>pTCVΩ<i>gbcO</i> (empty squares) strains. Tunicamycin, a general inhibitor of UDP-GlcNAc:lipid phosphate carrier transferase activities, inhibits the growth of WT and complemented strains but not that of <i>ΔgbcO</i> mutant suggesting that GbcO carries this activity. Experiments were performed in triplicate and results are reported as a percentage of the growth rate in absence of tunicamycin. Error bars represent ± S.E. of triplicate experiments.</p

    Fluorescent immunolocalization of the putative peptidoglycan hydrolase PcsB.

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    <p>Exponentially growing NEM316 WT, <i>ΔgbcO</i> mutant and Δ<i>gbcO</i>pTCVΩ<i>gbcO</i> complemented strains were harvested, transferred to glass slide, and fixed. IFM with anti-PcsB serum and DAPI staining were performed as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002756#s3" target="_blank">Materials and Methods</a>.</p

    Table_1.PDF

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    <p>Biofilm formation is crucial for bacterial community development and host colonization by Streptococcus salivarius, a pioneer colonizer and commensal bacterium of the human gastrointestinal tract. This ability to form biofilms depends on bacterial adhesion to host surfaces, and on the intercellular aggregation contributing to biofilm cohesiveness. Many S. salivarius isolates auto-aggregate, an adhesion process mediated by cell surface proteins. To gain an insight into the genetic factors of S. salivarius that dictate host adhesion and biofilm formation, we developed a screening method, based on the differential sedimentation of bacteria in semi-liquid conditions according to their auto-aggregation capacity, which allowed us to identify twelve mutations affecting this auto-aggregation phenotype. Mutations targeted genes encoding (i) extracellular components, including the CshA surface-exposed protein, the extracellular BglB glucan-binding protein, the GtfE, GtfG and GtfH glycosyltransferases and enzymes responsible for synthesis of cell wall polysaccharides (CwpB, CwpK), (ii) proteins responsible for the extracellular localization of proteins, such as structural components of the accessory SecA2Y2 system (Asp1, Asp2, SecA2) and the SrtA sortase, and (iii) the LiaR transcriptional response regulator. These mutations also influenced biofilm architecture, revealing that similar cell-to-cell interactions govern assembly of auto-aggregates and biofilm formation. We found that BglB, CshA, GtfH and LiaR were specifically associated with bacterial auto-aggregation, whereas Asp1, Asp2, CwpB, CwpK, GtfE, GtfG, SecA2 and SrtA also contributed to adhesion to host cells and host-derived components, or to interactions with the human pathogen Fusobacterium nucleatum. Our study demonstrates that our screening method could also be used to identify genes implicated in the bacterial interactions of pathogens or probiotics, for which aggregation is either a virulence trait or an advantageous feature, respectively.</p

    Image_1.PDF

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    <p>Biofilm formation is crucial for bacterial community development and host colonization by Streptococcus salivarius, a pioneer colonizer and commensal bacterium of the human gastrointestinal tract. This ability to form biofilms depends on bacterial adhesion to host surfaces, and on the intercellular aggregation contributing to biofilm cohesiveness. Many S. salivarius isolates auto-aggregate, an adhesion process mediated by cell surface proteins. To gain an insight into the genetic factors of S. salivarius that dictate host adhesion and biofilm formation, we developed a screening method, based on the differential sedimentation of bacteria in semi-liquid conditions according to their auto-aggregation capacity, which allowed us to identify twelve mutations affecting this auto-aggregation phenotype. Mutations targeted genes encoding (i) extracellular components, including the CshA surface-exposed protein, the extracellular BglB glucan-binding protein, the GtfE, GtfG and GtfH glycosyltransferases and enzymes responsible for synthesis of cell wall polysaccharides (CwpB, CwpK), (ii) proteins responsible for the extracellular localization of proteins, such as structural components of the accessory SecA2Y2 system (Asp1, Asp2, SecA2) and the SrtA sortase, and (iii) the LiaR transcriptional response regulator. These mutations also influenced biofilm architecture, revealing that similar cell-to-cell interactions govern assembly of auto-aggregates and biofilm formation. We found that BglB, CshA, GtfH and LiaR were specifically associated with bacterial auto-aggregation, whereas Asp1, Asp2, CwpB, CwpK, GtfE, GtfG, SecA2 and SrtA also contributed to adhesion to host cells and host-derived components, or to interactions with the human pathogen Fusobacterium nucleatum. Our study demonstrates that our screening method could also be used to identify genes implicated in the bacterial interactions of pathogens or probiotics, for which aggregation is either a virulence trait or an advantageous feature, respectively.</p
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