| 1. |
- Charpentier, E, et al.
(author)
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Mechanisms of antibiotic resistance and tolerance in Streptococcus pneumoniae.
- 2000
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In: Microbes and infection. - 1286-4579 .- 1769-714X. ; 2:15, s. 1855-64
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Journal article (peer-reviewed)abstract
- Streptococcus pneumoniae is a major pathogen causing potentially life-threatening community-acquired diseases in both the developed and developing world. Since 1967, there has been a dramatic increase in the incidence of penicillin-resistant and multiply antibiotic-resistant pneumococci worldwide. Prevention of access of the antibiotic to the target, inactivation of the antibiotic and alteration of the target are mechanisms that S. pneumoniae has developed to resist antibiotics. Recent studies on antibiotic-tolerant pneumococcal mutants permitted development of a novel model for the control of bacterial cell death.
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| 2. |
- Charpentier, E, et al.
(author)
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Regulation of growth inhibition at high temperature, autolysis, transformation and adherence in Streptococcus pneumoniae by clpC.
- 2000
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In: Molecular Microbiology. - 0950-382X .- 1365-2958. ; 37:4, s. 717-26
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Journal article (peer-reviewed)abstract
- The ClpC ATPase is a subfamily of HSP100/Clp molecular chaperones-regulators of proteolysis. By screening a library of loss of function mutants for the ability to survive treatment with penicillin, we identified the gene clpC. The corresponding protein was identified as a ClpC ATPase, sharing strong peptide sequence identity with ClpC of Bacillus subtilis, Listeria monocytogenes and Lactococcus lactis. Northern blot experiments showed that expression of clpC was induced in response to high temperature (40-42 degrees C) versus 37 degrees C, suggesting that ClpC is a heat shock protein. Insertional duplication mutagenesis of clpC resulted in increased tolerance to high temperature; a result in contrast to other bacterial Clp proteases. The clpC-deficient mutant formed long chains and failed to undergo lysis after treatment with penicillin or vancomycin. The effect of the clpC mutation extended to deficiency of adherence to the human type II alveolar cells. Finally, the clpC disruption resulted in decreased genetic transformation. Western blot analysis demonstrated that the mutant failed to express pneumolysin and the choline-binding proteins LytA, CbpA, CbpE, CbpF, CbpJ. These results suggest that the heat shock protein ClpC plays an essential complex pleiotropic role in pneumococcal physiology, including cell growth under heat stress, cell division, autolysis, adherence and transformation.
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| 3. |
- Novak, R, et al.
(author)
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Extracellular targeting of choline-binding proteins in Streptococcus pneumoniae by a zinc metalloprotease.
- 2000
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In: Molecular Microbiology. - 0950-382X .- 1365-2958. ; 36:2, s. 366-376
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Journal article (peer-reviewed)abstract
- A genetic-based search for surface proteins of Streptococcus pneumoniae involved in adhesion identified a putative zinc metalloprotease (ZmpB). ZmpB shared high amino acid sequence similarities with IgA1 proteases of Gram-positive bacteria, but ZmpB had neither IgA1 nor IgA2 protease activity. Analysis of a family of surface-expressed proteins, the choline-binding proteins (Cbp's), in a zmpB-deficient mutant demonstrated a global loss of surface expression of CbpA, CbpE, CbpF and CbpJ. CbpA was detected within the cytoplasm. The zmpB-deficient mutant also failed to lyse with penicillin, a sign of lack of function of the Cbp LytA. Immunodetection studies revealed that the autolysin (LytA), normally located on the cell wall, was trapped in the cytoplasm colocalized with DNA and the transformation protein CinA. Trafficking of CinA and RecA to the cell membrane during genetic competence was also not observed in the zmpB-deficient mutant. These results suggest a protease dependent regulatory mechanism governing the translocation of CinA and the Cbp's LytA and CbpA of S. pneumoniae.
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| 4. |
- Novak, R, et al.
(author)
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Signal transduction by a death signal peptide : uncovering the mechanism of bacterial killing by penicillin.
- 2000
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In: Molecular Cell. - 1097-2765 .- 1097-4164. ; 5:1, s. 49-57
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Journal article (peer-reviewed)abstract
- The binding of bactericidal antibiotics like penicillins, cephalosporins, and glycopeptides to their bacterial targets stops bacterial growth but does not directly cause cell death. A second process arising from the bacteria itself is necessary to trigger endogenous suicidal enzymes that dissolve the cell wall during autolysis. The signal and the trigger pathway for this event are completely unknown. Using S. pneumoniae as a model, we demonstrate that signal transduction via the two-component system VncR/S triggers multiple death pathways. We show that the signal sensed by VncR/S is a secreted peptide, Pep27, that initiates the cell death program. These data depict a novel model for the control of bacterial cell death.
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| 5. |
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