scholarly journals Role of Manganese-Containing Superoxide Dismutase in Oxidative Stress and Virulence of Streptococcus pneumoniae

2000 ◽  
Vol 68 (5) ◽  
pp. 2819-2826 ◽  
Author(s):  
Hasan Yesilkaya ◽  
Aras Kadioglu ◽  
Neill Gingles ◽  
Janet E. Alexander ◽  
Tim J. Mitchell ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Streptococcus Pneumoniae ◽  
Anaerobic Growth ◽  
Wild Type ◽  
Gene Encoding ◽  
Lower Growth ◽  
Redox Active ◽  
Lower Growth Rate

ABSTRACT Streptococcus pneumoniae was shown to contain two types of superoxide dismutase, MnSOD and FeSOD. Levels of MnSOD increased during growth in an aerobic environment. The sodA gene, encoding MnSOD, of virulent S. pneumoniae type 2 strain D39 was inactivated to give mutant D39HY1. Aerobically, D39HY1 had a lower growth rate than the wild type and exhibited susceptibility to the redox-active compound paraquat, but anaerobic growth of D39HY1 was identical to that of the wild type. Virulence studies showed that the median survival time of mice infected intranasally with D39HY1 was significantly longer than that of mice infected with the wild-type pneumococcus. In contrast to the wild type, D39HY1 did not multiply in lungs during the first 24 h but thereafter grew at the same rate as the wild type. Appearance in the bloodstream was also delayed, but growth in the blood was unimpaired by the sodA mutation. The pattern of inflammation in lungs infected with D39HY1 differed from that in wild-type-infected mice. After infection with D39HY1, neutrophils were densely packed around bronchioles, in contrast to the wild-type infection, where neutrophils were more diffusely localized.

scholarly journals Pneumococcal Surface Protein C Contributes to Sepsis Caused by Streptococcus pneumoniae in Mice

2004 ◽  
Vol 72 (5) ◽  
pp. 3077-3080 ◽  
Author(s):  
Francesco Iannelli ◽  
Damiana Chiavolini ◽  
Susanna Ricci ◽  
Marco Rinaldo Oggioni ◽  
Gianni Pozzi
Keyword(s):  
Streptococcus Pneumoniae ◽  
Protein C ◽  
Lethal Dose ◽  
Surface Protein ◽  
Infection Model ◽  
Wild Type ◽  
Mutant Strains ◽  
Type 3

ABSTRACT The role of pneumococcal surface protein C (PspC; also called SpsA, CbpA, and Hic) in sepsis by Streptococcus pneumoniae was investigated in a murine infection model. The pspC gene was deleted in strains D39 (type 2) and A66 (type 3), and the mutants were tested by being injected intravenously into mice. The animals infected with the mutant strains showed a significant increase in survival, with the 50% lethal dose up to 250-fold higher than that for the wild type. Our findings indicate that PspC affords a decisive contribution to sepsis development.

scholarly journals Comparative Virulence of Streptococcus pneumoniaeStrains with Insertion-Duplication, Point, and Deletion Mutations in the Pneumolysin Gene

1999 ◽  
Vol 67 (2) ◽  
pp. 981-985 ◽  
Author(s):  
Anne M. Berry ◽  
A. David Ogunniyi ◽  
David C. Miller ◽  
James C. Paton
Keyword(s):  
Amino Acids ◽  
Streptococcus Pneumoniae ◽  
Complement Activation ◽  
Point Mutations ◽  
Cytolytic Activity ◽  
Toxin Gene ◽  
Wild Type ◽  
Gene Encoding ◽  
Deletion Mutations

ABSTRACT Pneumolysin is a 471-amino-acid toxin produced byStreptococcus pneumoniae which has both cytolytic and complement activation properties. We have constructed a derivative of the type 2 S. pneumoniae strain D39 in which the portion of the pneumolysin gene encoding amino acids 55 to 437 has been deleted in-frame. The virulence of this strain (ΔPly) was compared with those of wild-type D39, a pneumolysin insertion-duplication mutant (PLN-A), and a derivative (PdT) carrying a toxin gene with three point mutations known to abolish both cytolytic activity and complement activation. PdT was intermediate in virulence between D39 and either PLN-A or ΔPly in a mouse intraperitoneal challenge model. This provides unequivocal evidence that pneumolysin has an additional property that is not abolished by point mutations which reduce cytotoxicity and complement activation to virtually undetectable levels.

scholarly journals Expression of Mycobacterium smegmatisPyrazinamidase in Mycobacterium tuberculosis Confers Hypersensitivity to Pyrazinamide and Related Amides

2000 ◽  
Vol 182 (19) ◽  
pp. 5479-5485 ◽  
Author(s):  
Helena I. M. Boshoff ◽  
Valerie Mizrahi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Intracellular Localization ◽  
Wild Type ◽  
Gene Encoding ◽  
Allelic Exchange ◽  
Mutant Strains ◽  
Established Role ◽  
Amidase Gene

ABSTRACT A pyrazinamidase (PZase)-deficient pncA mutant ofMycobacterium tuberculosis, constructed by allelic exchange, was used to investigate the effects of heterologous amidase gene expression on the susceptibility of this organism to pyrazinamide (PZA) and related amides. The mutant was highly resistant to PZA (MIC, >2,000 μg/ml), in accordance with the well-established role ofpncA in the PZA susceptibility of M. tuberculosis (A. Scorpio and Y. Zhang, Nat. Med. 2:662–667, 1996). Integration of the pzaA gene encoding the major PZase/nicotinamidase from Mycobacterium smegmatis (H. I. M. Boshoff and V. Mizrahi, J. Bacteriol. 180:5809–5814, 1998) or the M. tuberculosis pncA gene into the pncAmutant complemented its PZase/nicotinamidase defect. In bothpzaA- and pncA-complemented mutant strains, the PZase activity was detected exclusively in the cytoplasm, suggesting an intracellular localization for PzaA and PncA. ThepzaA-complemented strain was hypersensitive to PZA (MIC, ≤10 μg/ml) and nicotinamide (MIC, ≥20 μg/ml) and was also sensitive to benzamide (MIC, 20 μg/ml), unlike the wild-type andpncA-complemented mutant strains, which were highly resistant to this amide (MIC, >500 μg/ml). This finding was consistent with the observation that benzamide is hydrolyzed by PzaA but not by PncA. Overexpression of PzaA also conferred sensitivity to PZA, nicotinamide, and benzamide on M. smegmatis (MIC, 150 μg/ml in all cases) and rendered Escherichia colihypersensitive for growth at low pH.

scholarly journals Surface-Exposed Adeno-Associated Virus Vp1-NLS Capsid Fusion Protein Rescues Infectivity of Noninfectious Wild-Type Vp2/Vp3 and Vp3-Only Capsids but Not That of Fivefold Pore Mutant Virions

2007 ◽  
Vol 81 (15) ◽  
pp. 7833-7843 ◽  
Author(s):  
Joshua C. Grieger ◽  
Jarrod S. Johnson ◽  
Brittney Gurda-Whitaker ◽  
Mavis Agbandje-McKenna ◽  
R. Jude Samulski
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Wild Type ◽  
Dot Blot ◽  
Adeno Associated Virus ◽  
N Terminus ◽  
Localization Signal ◽  
Significant Effort

ABSTRACT Over the past 2 decades, significant effort has been dedicated to the development of adeno-associated virus (AAV) as a vector for human gene therapy. However, understanding of the virus with respect to the functional domains of the capsid remains incomplete. In this study, the goal was to further examine the role of the unique Vp1 N terminus, the N terminus plus the recently identified nuclear localization signal (NLS) (J. C. Grieger, S. Snowdy, and R. J. Samulski, J. Virol 80:5199-5210, 2006), and the virion pore at the fivefold axis in infection. We generated two Vp1 fusion proteins (Vp1 and Vp1NLS) linked to the 8-kDa chemokine domain of rat fractalkine (FKN) for the purpose of surface exposure upon assembly of the virion, as previously described (K. H. Warrington, Jr., O. S. Gorbatyuk, J. K. Harrison, S. R. Opie, S. Zolotukhin, and N. Muzyczka, J. Virol 78:6595-6609, 2004). The unique Vp1 N termini were found to be exposed on the surfaces of these capsids and maintained their phospholipase A2 (PLA2) activity, as determined by native dot blot Western and PLA2 assays, respectively. Incorporation of the fusions into AAV type 2 capsids lacking a wild-type Vp1, i.e., Vp2/Vp3 and Vp3 capsid only, increased infectivity by 3- to 5-fold (Vp1FKN) and 10- to 100-fold (Vp1NLSFKN), respectively. However, the surface-exposed fusions did not restore infectivity to AAV virions containing mutations at a conserved leucine (Leu336Ala, Leu336Cys, or Leu336Trp) located at the base of the fivefold pore. EM analyses suggest that Leu336 may play a role in global structural changes to the virion directly impacting downstream conformational changes essential for infectivity and not only have local effects within the pore, as previously suggested.

scholarly journals AP-1 elements and TCL1 protein regulate expression of the gene encoding protein tyrosine phosphatase PTPROt in leukemia

Blood ◽  
2011 ◽  
Vol 118 (23) ◽  
pp. 6132-6140 ◽  
Author(s):  
Tasneem Motiwala ◽  
Nicola Zanesi ◽  
Jharna Datta ◽  
Satavisha Roy ◽  
Huban Kutay ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Lymphocytic Leukemia ◽  
Potential Mechanism ◽  
Wild Type ◽  
Truncated Form ◽  
Gene Encoding ◽  
Protein Tyrosine ◽  
Encoding Protein

Abstract We previously demonstrated that the gene encoding PTPROt, the truncated form of protein tyrosine phosphatase receptor type O expressed predominantly in hematopoietic cells, is a candidate tumor suppressor and is down-regulated in chronic lymphocytic leukemia (CLL). Here, we show that PTPROt expression is significantly reduced in CD19+ spleen B cells from Eμ-T cell leukemia 1 (TCL1) transgenic mice relative to the wild-type mice. Strikingly, as much as a 60% decrease in PTPROt expression occurs at 7 weeks independently of promoter methylation. To elucidate the potential mechanism for this early suppression of PTPROt in these mice, we explored the role of activating protein-1 (AP-1) in its expression. We first demonstrate that AP-1 activation by 12-O-tetradecanoylphorbol-13-acetate induces PTPROt expression with concurrent recruitment of c-fos and c-jun to its promoter. The PTPROt promoter is also responsive to over- and underexpression of AP-1, confirming the role of AP-1 in PTPROt expression. Next, we demonstrate that TCL1 can repress the PTPROt promoter by altering c-fos expression and c-jun activation state. Finally, using primary CLL cells we have shown an inverse relationship between TCL1 and PTPROt expression. These findings further substantiate the role of TCL1 in PTPROt suppression and its importance in the pathogenesis of CLL.

scholarly journals Histidine Decarboxylase Deficiency Prevents Autoimmune Diabetes in NOD Mice

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Manal Alkan ◽  
François Machavoine ◽  
Rachel Rignault ◽  
Julie Dam ◽  
Michel Dy ◽  
...  
Keyword(s):  
Histidine Decarboxylase ◽  
Autoimmune Diabetes ◽  
Nod Mice ◽  
Wild Type ◽  
Gene Encoding ◽  
Nonobese Diabetic ◽  
Endogenous Histamine ◽  
Wild Type Counterpart

Recent evidence has highlighted the role of histamine in inflammation. Since this monoamine has also been strongly implicated in the pathogenesis of type-1 diabetes, we assessed its effect in the nonobese diabetic (NOD) mouse model. To this end, we used mice (inactivated) knocked out for the gene encoding histidine decarboxylase, the unique histamine-forming enzyme, backcrossed on a NOD genetic background. We found that the lack of endogenous histamine in NOD HDC−/−mice decreased the incidence of diabetes in relation to their wild-type counterpart. Whereas the proportion of regulatory T and myeloid-derived suppressive cells was similar in both strains, histamine deficiency was associated with increased levels of immature macrophages, as compared with wild-type NOD mice. Concerning the cytokine pattern, we found a decrease in circulating IL-12 and IFN-γin HDC−/−mice, while IL-6 or leptin remained unchanged, suggesting that histamine primarily modulates the inflammatory environment. Paradoxically, exogenous histamine given to NOD HDC−/−mice provided also protection against T1D. Our study supports the notion that histamine is involved in the pathogenesis of diabetes, thus providing additional evidence for its role in the regulation of the immune response.

scholarly journals Cryptococcus neoformans Evades Pulmonary Immunity by Modulating Xylose Precursor Transport

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Lucy X. Li ◽  
Camaron R. Hole ◽  
Javier Rangel-Moreno ◽  
Shabaana A. Khader ◽  
Tamara L. Doering
Keyword(s):  
Cryptococcus Neoformans ◽  
Mutant Strain ◽  
Fungal Pathogen ◽  
Wild Type ◽  
Content Type ◽  
Helper Cell Type ◽  
Lymphoid Structures ◽  
Type Infection

ABSTRACT Cryptococcus neoformans is a fungal pathogen that kills almost 200,000 people each year and is distinguished by abundant and unique surface glycan structures that are rich in xylose. A mutant strain of C. neoformans that cannot transport xylose precursors into the secretory compartment is severely attenuated in virulence in mice yet surprisingly is not cleared. We found that this strain failed to induce the nonprotective T helper cell type 2 (Th2) responses characteristic of wild-type infection, instead promoting sustained interleukin 12p40 (IL-12p40) induction and increased IL-17A (IL-17) production. It also stimulated dendritic cells to release high levels of proinflammatory cytokines, a behavior we linked to xylose expression. We further discovered that inducible bronchus-associated lymphoid tissue (iBALT) forms in response to infection with either wild-type cryptococci or the mutant strain with reduced surface xylose; although iBALT formation is slowed in the latter case, the tissue is better organized. Finally, our temporal studies suggest that lymphoid structures in the lung restrict the spread of mutant fungi for at least 18 weeks after infection, which is in contrast to ineffective control of the pathogen after infection with wild-type cells. These studies demonstrate the role of xylose in modulation of host response to a fungal pathogen and show that cryptococcal infection triggers iBALT formation.

scholarly journals Deletion of the rpoZ gene, encoding the ω subunit of RNA polymerase, results in pleiotropic surface-related phenotypes in Mycobacterium smegmatis

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1741-1750 ◽  
Author(s):  
Renjith Mathew ◽  
Raju Mukherjee ◽  
Radhakrishnan Balachandar ◽  
Dipankar Chatterji
Keyword(s):  
Rna Polymerase ◽  
Mycobacterium Smegmatis ◽  
Biofilm Formation ◽  
Physiological Role ◽  
Wild Type ◽  
Gene Encoding ◽  
Biofilm Growth ◽  
Mutant Bacterium ◽  
Sliding Motility

The ω subunit, the smallest subunit of bacterial RNA polymerase, is known to be involved in maintaining the conformation of the β′ subunit and aiding its recruitment to the rest of the core enzyme assembly in Escherichia coli. It has recently been shown in Mycobacterium smegmatis, by creating a deletion mutation of the rpoZ gene encoding ω, that the physiological role of the ω subunit also includes providing physical protection to β′. Interestingly, the mutant had altered colony morphology. This paper demonstrates that the mutant mycobacterium has pleiotropic phenotypes including reduced sliding motility and defective biofilm formation. Analysis of the spatial arrangement of biofilms by electron microscopy suggests that the altered phenotype of the mutant arises from a deficiency in generation of extracellular matrix. Complementation of the mutant strain with a copy of the wild-type rpoZ gene integrated in the bacterial chromosome restored both sliding motility and biofilm formation to the wild-type state, unequivocally proving the role of ω in the characteristics observed for the mutant bacterium. Analysis of the cell wall composition demonstrated that the mutant bacterium had an identical glycopeptidolipid profile to the wild-type, but failed to synthesize the short-chain mycolic acids characteristic of biofilm growth in M. smegmatis.

scholarly journals Double-Edged Role of Interleukin 17A in Streptococcus pneumoniae Pathogenesis During Influenza Virus Coinfection

2019 ◽  
Vol 220 (5) ◽  
pp. 902-912 ◽  
Author(s):  
Ganesh Ambigapathy ◽  
Taylor Schmit ◽  
Ram Kumar Mathur ◽  
Suba Nookala ◽  
Saad Bahri ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Puerto Rico ◽  
Streptococcus Pneumoniae ◽  
Influenza A ◽  
Invasive Disease ◽  
Wild Type ◽  
Interleukin 17A ◽  
Influenza A H1n1 ◽  
Virus Influenza

AbstractBackgroundWe sought to determine the role of host interleukin 17A (IL-17A) response against colonizing Streptococcus pneumoniae, and its transition to a pathogen during coinfection with an influenza virus, influenza A H1N1 A/Puerto Rico/8/1934 (PR8).MethodWild-type (WT) C57BL/6 mice were intranasally inoculated with S. pneumoniae serotype 6A to establish colonization and later infected with the influenza strain, PR8, resulting in invasive S. pneumoniae disease. The role of the IL-17A response in colonization and coinfection was investigated in WT, RoRγt−/− and RAG1−/− mice with antibody-mediated depletion of IL-17A (WT) and CD90 cells (RAG1−/−).ResultsRAG1−/− mice did not clear colonization and IL-17A neutralization impaired 6A clearance in WT mice. RoRγt−/− mice also had reduced clearance. S. pneumoniae–PR8 coinfection elicited a robust IL-17A response in the nasopharynx; IL-17A neutralization reduced S. pneumoniae invasive disease. RoRγt−/− mice also had reduced S. pneumoniae disease in a coinfection model. Depletion of CD90+ cells suppressed the IL-17A response and reduced S. pneumoniae invasion in RAG1−/− mice.ConclusionOur data show that although IL-17A reduces S. pneumoniae colonization, coinfection with influenza virus elicits a robust innate IL-17A response that promotes inflammation and S. pneumoniae disease in the nasopharynx.

scholarly journals Mutations in PMR1 suppress oxidative damage in yeast cells lacking superoxide dismutase.

1995 ◽  
Vol 15 (3) ◽  
pp. 1382-1388 ◽  
Author(s):  
P J Lapinskas ◽  
K W Cunningham ◽  
X F Liu ◽  
G R Fink ◽  
V C Culotta
Keyword(s):  
Superoxide Dismutase ◽  
Oxidative Damage ◽  
Eukaryotic Cell ◽  
Yeast Cells ◽  
Manganese Ions ◽  
Wild Type ◽  
Sod1 Gene ◽  
Gene Encoding ◽  
Manganese Ion ◽  
P Type

Mutants of Saccharomyces cerevisiae lacking a functional SOD1 gene encoding Cu/Zn superoxide dismutase (SOD) are sensitive to atmospheric levels of oxygen and are auxotrophic for lysine and methionine when grown in air. We have previously shown that these defects of SOD-deficient yeast cells can be overcome through mutations in either the BSD1 or BSD2 (bypass SOD defects) gene. In this study, the wild-type allele of BSD1 was cloned by functional complementation and was physically mapped to the left arm of chromosome VII. BSD1 is identical to PMR1, encoding a member of the P-type ATPase family that localizes to the Golgi apparatus. PMR1 is thought to function in calcium metabolism, and we provide evidence that PMR1 also participates in the homeostasis of manganese ions. Cells lacking a functional PMR1 gene accumulate elevated levels of intracellular manganese and are also extremely sensitive to manganese ion toxicity. We demonstrate that mutations in PMR1 bypass SOD deficiency through a mechanism that depends on extracellular manganese. Collectively, these findings indicate that oxidative damage in a eukaryotic cell can be prevented through alterations in manganese homeostasis.

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