scholarly journals Isocitrate Dehydrogenase Is Important for Nitrosative Stress Resistance in Cryptococcus neoformans, but Oxidative Stress Resistance Is Not Dependent on Glucose-6-Phosphate Dehydrogenase

2010 ◽  
Vol 9 (6) ◽  
pp. 971-980 ◽  
Author(s):  
Sarah M. Brown ◽  
Rajendra Upadhya ◽  
James D. Shoemaker ◽  
Jennifer K. Lodge
Keyword(s):  
Oxidative Stress ◽  
Cryptococcus Neoformans ◽  
Stress Resistance ◽  
Isocitrate Dehydrogenase ◽  
Nitrosative Stress ◽  
Stress Sensitivity ◽  
Wild Type ◽  
Oxidative And Nitrosative Stress ◽  
Content Type ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT The opportunistic intracellular fungal pathogen Cryptococcus neoformans depends on many antioxidant and denitrosylating proteins and pathways for virulence in the immunocompromised host. These include the glutathione and thioredoxin pathways, thiol peroxidase, cytochrome c peroxidase, and flavohemoglobin denitrosylase. All of these ultimately depend on NADPH for either catalytic activity or maintenance of a reduced, functional form. The need for NADPH during oxidative stress is well established in many systems, but a role in resistance to nitrosative stress has not been as well characterized. In this study we investigated the roles of two sources of NADPH, glucose-6-phosphate dehydrogenase (Zwf1) and NADP+-dependent isocitrate dehydrogenase (Idp1), in production of NADPH and resistance to oxidative and nitrosative stress. Deletion of ZWF1 in C. neoformans did not result in an oxidative stress sensitivity phenotype or changes in the amount of NADPH produced during oxidative stress compared to those for the wild type. Deletion of IDP1 resulted in greater sensitivity to nitrosative stress than to oxidative stress. The amount of NADPH increased 2-fold over that in the wild type during nitrosative stress, and yet the idp1Δ strain accumulated more mitochondrial damage than the wild type during nitrosative stress. This is the first report of the importance of Idp1 and NADPH for nitrosative stress resistance.

scholarly journals Cryptococcus neoformans Phosphoinositide-Dependent Kinase 1 (PDK1) Ortholog Is Required for Stress Tolerance and Survival in Murine Phagocytes

2012 ◽  
Vol 12 (1) ◽  
pp. 12-22 ◽  
Author(s):  
Yeissa Chabrier-Roselló ◽  
Kimberly J. Gerik ◽  
Kristy Koselny ◽  
Louis DiDone ◽  
Jennifer K. Lodge ◽  
...  
Keyword(s):  
Cell Wall ◽  
Stress Tolerance ◽  
Cryptococcus Neoformans ◽  
Nitrosative Stress ◽  
Galleria Mellonella ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Oxidative And Nitrosative Stress ◽  
Independent Manner ◽  
Content Type

ABSTRACTCryptococcus neoformansPKH2-01andPKH2-02are orthologous to mammalian PDK1 kinase genes. Although orthologs of these kinases have been extensively studied inS. cerevisiae, little is known about their function in pathogenic fungi. In this study, we show thatPKH2-02but notPKH2-01is required forC. neoformansto tolerate cell wall, oxidative, nitrosative, and antifungal drug stress. Deletion ofPKH2-02leads to decreased basal levels of Pkc1 activity and, consequently, reduced activation of the cell wall integrity mitogen-activated protein kinase (MAPK) pathway in response to cell wall, oxidative, and nitrosative stress.PKH2-02function also is required for tolerance of fluconazole and amphotericin B, two important drugs for the treatment of cryptococcosis. Furthermore, OSU-03012, an inhibitor of human PDK1, is synergistic and fungicidal in combination with fluconazole. Using aGalleria mellonellamodel of low-temperature cryptococcosis, we found thatPKH2-02is also required for virulence in a temperature-independent manner. Consistent with the hypersensitivity of thepkh2-02Δ mutant to oxidative and nitrosative stress, this mutant shows decreased survival in murine phagocytes compared to that of wild-type (WT) cells. In addition, we show that deletion ofPKH2-02affects the interaction betweenC. neoformansand phagocytes by decreasing its ability to suppress production of tumor necrosis factor alpha (TNF-α) and reactive oxygen species. Taken together, our studies demonstrate that Pkh2-02-mediated signaling inC. neoformansis crucial for stress tolerance, host-pathogen interactions, and both temperature-dependent and -independent virulence.

scholarly journals Proline Metabolism IncreaseskatGExpression and Oxidative Stress Resistance in Escherichia coli

2014 ◽  
Vol 197 (3) ◽  
pp. 431-440 ◽  
Author(s):  
Lu Zhang ◽  
James R. Alfano ◽  
Donald F. Becker
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Mutant Strain ◽  
Stress Resistance ◽  
Proline Metabolism ◽  
Wild Type ◽  
Content Type ◽  
Oxidative Stress Resistance ◽  
Proline Utilization

The oxidation ofl-proline to glutamate in Gram-negative bacteria is catalyzed by the proline utilization A (PutA) flavoenzyme, which contains proline dehydrogenase (PRODH) and Δ1-pyrroline-5-carboxylate (P5C) dehydrogenase domains in a single polypeptide. Previous studies have suggested that aside from providing energy, proline metabolism influences oxidative stress resistance in different organisms. To explore this potential role and the mechanism, we characterized the oxidative stress resistance of wild-type andputAmutant strains ofEscherichia coli. Initial stress assays revealed that theputAmutant strain was significantly more sensitive to oxidative stress than the parental wild-type strain. Expression of PutA in theputAmutant strain restored oxidative stress resistance, confirming that depletion of PutA was responsible for the oxidative stress phenotype. Treatment of wild-type cells with proline significantly increased hydroperoxidase I (encoded bykatG) expression and activity. Furthermore, the ΔkatGstrain failed to respond to proline, indicating a critical role for hydroperoxidase I in the mechanism of proline protection. The global regulator OxyR activates the expression ofkatGalong with several other genes involved in oxidative stress defense. In addition tokatG, proline increased the expression ofgrxA(glutaredoxin 1) andtrxC(thioredoxin 2) of the OxyR regulon, implicating OxyR in proline protection. Proline oxidative metabolism was shown to generate hydrogen peroxide, indicating that proline increases oxidative stress tolerance inE. colivia a preadaptive effect involving endogenous hydrogen peroxide production and enhanced catalase-peroxidase activity.

scholarly journals Inactivation of the Organic Hydroperoxide Stress Resistance Regulator OhrR Enhances Resistance to Oxidative Stress and Isoniazid in Mycobacterium smegmatis

2014 ◽  
Vol 197 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Sankaralingam Saikolappan ◽  
Kishore Das ◽  
Subramanian Dhandayuthapani
Keyword(s):  
Oxidative Stress ◽  
Mutant Strain ◽  
Stress Resistance ◽  
Mycobacterium Smegmatis ◽  
Cumene Hydroperoxide ◽  
Wild Type ◽  
Mobility Shift ◽  
Organic Hydroperoxide ◽  
Content Type ◽  
Protein Levels

The organic hydroperoxide stress resistance regulator (OhrR) is a MarR type of transcriptional regulator that primarily regulates the expression of organic hydroperoxide reductase (Ohr) in bacteria. In mycobacteria, the genes encoding these proteins exist in only a few species, which include the fast-growing organismMycobacterium smegmatis. To delineate the roles of Ohr and OhrR in defense against oxidative stress inM. smegmatis, strains lacking the expression of these proteins were constructed by deleting theohrRandohrgenes, independently and together, through homologous recombination. The OhrR mutant strain (MSΔohrR) showed severalfold upregulation of Ohr expression, which could be observed at both the transcript and protein levels. Similar upregulation of Ohr expression was also noticed in anM. smegmatiswild-type strain (MSWt) induced with cumene hydroperoxide (CHP) andt-butyl hydroperoxide (t-BHP). The elevated Ohr expression in MSΔohrR correlated with heightened resistance to oxidative stress due to CHP andt-BHP and to inhibitory effects due to the antituberculosis drug isoniazid (INH). Further, this mutant strain exhibited significantly enhanced survival in the intracellular compartments of macrophages. In contrast, the strains lacking either Ohr alone (MSΔohr) or both Ohr and OhrR (MSΔohr-ohrR) displayed limited or no resistance to hydroperoxides and INH. Additionally, these strains showed no significant differences in intracellular survival from the wild type. Electrophoretic mobility shift assays (EMSAs) revealed that the overexpressed and purified OhrR interacts with theohr-ohrRintergenic region with a greater affinity and this interaction is contingent upon the redox state of the OhrR. These findings suggest that Ohr-OhrR is an important peroxide stress response system inM. smegmatis.

scholarly journals Upregulation of Cysteine Synthase and Cystathionine β-Synthase Contributes to Leishmania braziliensis Survival under Oxidative Stress

2015 ◽  
Vol 59 (8) ◽  
pp. 4770-4781 ◽  
Author(s):  
Ibeth Romero ◽  
Jair Téllez ◽  
Alvaro José Romanha ◽  
Mario Steindel ◽  
Edmundo Carlos Grisard
Keyword(s):  
Oxidative Stress ◽  
Protein Expression ◽  
Nitrosative Stress ◽  
De Novo ◽  
Stress Conditions ◽  
Leishmania Braziliensis ◽  
Oxidative And Nitrosative Stress ◽  
Cysteine Synthase ◽  
Content Type

ABSTRACTCysteine metabolism is considered essential for the crucial maintenance of a reducing environment in trypanosomatids due to its importance as a precursor of trypanothione biosynthesis. Expression, activity, functional rescue, and overexpression of cysteine synthase (CS) and cystathionine β-synthase (CβS) were evaluated inLeishmania braziliensispromastigotes and intracellular amastigotes underin vitrostress conditions induced by hydrogen peroxide (H2O2),S-nitroso-N-acetylpenicillamine, or antimonial compounds. Our results demonstrate a stage-specific increase in the levels of protein expression and activity ofL. braziliensisCS (LbrCS) andL. braziliensisCβS (LbrCβS), resulting in an increment of total thiol levels in response to both oxidative and nitrosative stress. The rescue of the CS activity inTrypanosoma rangeli, a trypanosome that does not perform cysteine biosynthesisde novo, resulted in increased rates of survival of epimastigotes expressing the LbrCS under stress conditions compared to those of wild-type parasites. We also found that the ability ofL. braziliensispromastigotes and amastigotes overexpressing LbrCS and LbrCβS to resist oxidative stress was significantly enhanced compared to that of nontransfected cells, resulting in a phenotype far more resistant to treatment with the pentavalent form of Sbin vitro. In conclusion, the upregulation of protein expression and increment of the levels of LbrCS and LbrCβS activity alter parasite resistance to antimonials and may influence the efficacy of antimony treatment of New World leishmaniasis.

scholarly journals Cdk8 and Ssn801 Regulate Oxidative Stress Resistance and Virulence inCryptococcus neoformans

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Andrew L. Chang ◽  
Yiming Kang ◽  
Tamara L. Doering
Keyword(s):  
Oxidative Stress ◽  
Rna Polymerase Ii ◽  
Cryptococcus Neoformans ◽  
Stress Resistance ◽  
Mediator Complex ◽  
Mammalian Host ◽  
Mitochondrial Morphology ◽  
Content Type ◽  
Oxidative Stress Resistance

ABSTRACTCryptococcus neoformanskills 200,000 people worldwide each year. After inhalation, this environmental yeast proliferates either extracellularly or within host macrophages. Under conditions of immunocompromise, cryptococci disseminate from the lungs to the brain, causing a deadly meningoencephalitis that is difficult and expensive to treat. Cryptococcal adaptation to the harsh lung environment is a critical first step in its pathogenesis, and consequently a compelling topic of study. This adaptation is mediated by a complex transcriptional program that integrates cellular responses to environmental stimuli. Although several key regulators in this process have been examined, one that remains understudied inC. neoformansis the Mediator complex. In other organisms, this complex promotes transcription of specific genes by increasing assembly of the RNA polymerase II preinitiation complex. We focused on the Kinase Module of Mediator, which consists of cyclin C (Ssn801), cyclin-dependent kinase 8 (Cdk8), Med12, and Med13. This module provides important inhibitory control of Mediator complex assembly and activity. Using transcriptomics, we discovered that Cdk8 and Ssn801 together regulate cryptococcal functions such as the ability to grow on acetate and the response to oxidative stress, both of which were experimentally validated. Deletion ofCDK8yielded altered mitochondrial morphology and the dysregulation of genes involved in oxidation-reduction processes. This strain exhibited increased susceptibility to oxidative stress, resulting in an inability of mutant cells to proliferate within phagocytes, decreased lung burdens, and attenuated virulencein vivo. These findings increase our understanding of cryptococcal adaptation to the host environment and its regulation of oxidative stress resistance and virulence.IMPORTANCECryptococcus neoformansis a fungal pathogen that primarily affects severely immunocompromised patients, resulting in 200,000 deaths every year. This yeast occurs in the environment and can establish disease upon inhalation into the lungs of a mammalian host. In this harsh environment it must survive engulfment by host phagocytes, including the oxidative stresses it experiences inside them. To adapt to these challenging conditions,C. neoformansdeploys a variety of regulatory proteins to alter gene expression levels and enhance its ability to survive. We have elucidated the role of a protein complex that regulates the cryptococcal response to oxidative stress, survival within phagocytes, and ability to cause disease. These findings are important because they advance our understanding of cryptococcal disease, which we hope will help in the efforts to control this devastating infection.

Two glutathione peroxidases in the fungal pathogen Cryptococcus neoformans are expressed in the presence of specific substrates

Microbiology ◽  
2005 ◽  
Vol 151 (8) ◽  
pp. 2573-2581 ◽  
Author(s):  
Tricia A. Missall ◽  
Jocie F. Cherry-Harris ◽  
Jennifer K. Lodge
Keyword(s):  
Nitric Oxide ◽  
Glutathione Peroxidase ◽  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Nitrosative Stress ◽  
Cumene Hydroperoxide ◽  
Wild Type ◽  
Oxidative And Nitrosative Stress ◽  
Glutathione Peroxidases ◽  
Response To Stress

Glutathione peroxidases catalyse the reduction of peroxides by reduced glutathione. To determine if these enzymes are important for resistance to oxidative stress and evasion of the innate immune system by the fungal pathogen Cryptococcus neoformans, two glutathione peroxidase homologues, which share 38 % identity, were identified and investigated. In this study, these peroxidases, Gpx1 and Gpx2, their localization, their contribution to total glutathione peroxidase activity, and their importance to the oxidative and nitrosative stress resistance of C. neoformans are described. It is shown that the two glutathione peroxidase genes are differentially expressed in response to stress. While both GPX1 and GPX2 are induced during t-butylhydroperoxide or cumene hydroperoxide stress and repressed during nitric oxide stress, only GPX2 is induced in response to hydrogen peroxide stress. Deletion mutants of each and both of the glutathione peroxidases were generated, and it was found that they are sensitive to various peroxide stresses while showing wild-type resistance to other oxidant stresses, such as superoxide and nitric oxide. While the glutathione peroxidase mutants are slightly sensitive to oxidant killing by macrophages, they exhibit wild-type virulence in a mouse model of cryptococcosis.

scholarly journals Loss of SigB in Listeria monocytogenes Strains EGD-e and 10403S Confers Hyperresistance to Hydrogen Peroxide in Stationary Phase under Aerobic Conditions

2016 ◽  
Vol 82 (15) ◽  
pp. 4584-4591 ◽  
Author(s):  
Marcia Boura ◽  
Ciara Keating ◽  
Kevin Royet ◽  
Ranju Paudyal ◽  
Beth O'Donoghue ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Listeria Monocytogenes ◽  
Stationary Phase ◽  
Stress Resistance ◽  
Wild Type ◽  
Content Type ◽  
Stress Genes ◽  
Reverse Transcription Pcr ◽  
Stress Gene

ABSTRACTSigB is the main stress gene regulator inListeria monocytogenesaffecting the expression of more than 150 genes and thus contributing to multiple-stress resistance. Despite its clear role in most stresses, its role in oxidative stress is uncertain, as results accompanying the loss ofsigBrange from hyperresistance to hypersensitivity. Previously, these differences have been attributed to strain variation. In this study, we show conclusively that unlike for all other stresses, loss ofsigBresults in hyperresistance to H2O2(more than 8 log CFU ml−1compared to the wild type) in aerobically grown stationary-phase cultures ofL. monocytogenesstrains 10403S and EGD-e. Furthermore, growth at 30°C resulted in higher resistance to oxidative stress than that at 37°C. Oxidative stress resistance seemed to be higher with higher levels of oxygen. Under anaerobic conditions, the loss of SigB in 10403S did not affect survival against H2O2, while in EGD-e, it resulted in a sensitive phenotype. During exponential phase, minor differences occurred, and this result was expected due to the absence ofsigBtranscription. Catalase tests were performed under all conditions, and stronger catalase results corresponded well with a higher survival rate, underpinning the important role of catalase in this phenotype. Furthermore, we assessed the catalase activity in protein lysates, which corresponded with the catalase tests and survival. In addition, reverse transcription-PCR (RT-PCR) showed no differences in transcription between the wild type and the ΔsigBmutant in various oxidative stress genes. Further investigation of the molecular mechanism behind this phenotype and its possible consequences for the overall phenotype ofL. monocytogenesare under way.IMPORTANCESigB is the most important stress gene regulator inL. monocytogenesand other Gram-positive bacteria. Its increased expression during stationary phase results in resistance to multiple stresses. However, despite its important role in general stress resistance, its expression is detrimental for the cell in the presence of oxidative stress, as it promotes hypersensitivity against hydrogen peroxide. This peculiar phenotype is an important element of the physiology ofL. monocytogenes, and it might help us explain the behavior of this organism in environments where oxidative stress is present.

Streblus asper Lour. exerts MAPK and SKN-1 mediated anti-aging, anti-photoaging activities and imparts neuroprotection by ameliorating Aβ in Caenorhabditis elegans

2021 ◽  
pp. 1-17
Author(s):  
Mani Iyer Prasanth ◽  
James Michael Brimson ◽  
Dicson Sheeja Malar ◽  
Anchalee Prasansuklab ◽  
Tewin Tencomnao
Keyword(s):  
Oxidative Stress ◽  
Caenorhabditis Elegans ◽  
Stress Resistance ◽  
Vital Role ◽  
Transgenic Strain ◽  
Wild Type ◽  
Neuroprotective Effects ◽  
C Elegans ◽  
Streblus Asper

BACKGROUND: Streblus asper Lour., has been reported to have anti-aging and neuroprotective efficacies in vitro. OBJECTIVE: To analyze the anti-aging, anti-photoaging and neuroprotective efficacies of S. asper in Caenorhabditis elegans. METHODS: C. elegans (wild type and gene specific mutants) were treated with S. asper extract and analyzed for lifespan and other health benefits through physiological assays, fluorescence microscopy, qPCR and Western blot. RESULTS: The plant extract was found to increase the lifespan, reduce the accumulation of lipofuscin and modulate the expression of candidate genes. It could extend the lifespan of both daf-16 and daf-2 mutants whereas the pmk-1 mutant showed no effect. The activation of skn-1 was observed in skn-1::GFP transgenic strain and in qPCR expression. Further, the extract can extend the lifespan of UV-A exposed nematodes along with reducing ROS levels. Additionally, the extract also extends lifespan and reduces paralysis in Aβ transgenic strain, apart from reducing Aβ expression. CONCLUSIONS: S. asper was able to extend the lifespan and healthspan of C. elegans which was independent of DAF-16 pathway but dependent on SKN-1 and MAPK which could play a vital role in eliciting the anti-aging, anti-photoaging and neuroprotective effects, as the extract could impart oxidative stress resistance and neuroprotection.

scholarly journals The role of oxidative and nitrosative stress in the pathology of osteoarthritis: Novel candidate biomarkers for quantification of degenerative changes in the knee joint

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Alexander Franz ◽  
Laura Joseph ◽  
Constantin Mayer ◽  
Jan-Frieder Harmsen ◽  
Holger Schrumpf ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Synovial Fluid ◽  
Knee Joint ◽  
Human Serum ◽  
Synovial Membrane ◽  
Nitrosative Stress ◽  
Control Groups ◽  
Oxidative And Nitrosative Stress ◽  
And Oxidative Stress

Osteoarthritis (OA) is the most frequently diagnosed joint disorder worldwide with increasing prevalence and crucial impact on the quality of life of affected patients through chronic pain, decreasing mobility and invalidity. Although some risk factors, such as age, obesity and previous joint injury are well established, the exact pathogenesis of OA on a cellular and molecular level remains less understood. Today, the role of nitrosative and oxidative stress has not been investigated conclusively in the pathogenesis of OA yet. Therefore, the objective of this study was to identify biological substances for oxidative and nitrosative stress, which mirror the degenerative processes in an osteoarthritic joint. 69 patients suffering from a diagnosed knee pain participated in this study. Based on the orthopedic diagnosis, patients were classified into an osteoarthritis group (OAG, n=24) or in one of two control groups (meniscopathy, CG1, n=11; anterior cruciate ligament rupture, CG2, n=34). Independently from the study protocol, all patients underwent an invasive surgical intervention which was used to collect samples from the synovial membrane, synovial fluid and human serum. Synovial biopsies were analyzed histopathologically for synovitis (Krenn-Score) and immunohistochemically for detection of end products of oxidative (8-isoprostane F2α) and nitrosative (3-nitrotyrosine) stress. Additionally, the fluid samples were analyzed for 8-isoprostane F2α and 3-nitrotyrosine by competitive ELISA method. The analyzation of inflammation in synovial biopsies revealed a slight synovitis in all three investigated groups. Detectable concentrations of 3-nitrotyrosine were reported in all three investigated groups without showing any significant differences between the synovial biopsies, fluid or human serum. In contrast, significant increased concentrations of 8-isoprostane F2α were detected in OAG compared to both control groups. Furthermore, our data showed a significant correlation between the histopathological synovitis and oxidative stress in OAG (r=0.728, P<0.01). There were no significant differences between the concentrations of 8-isoprostane F2α in synovial fluid and human serum. The findings of the current study support the hypothesis that oxidative and nitrosative stress are components of the multi-factory pathophysiological formation of OA. It seems reasonable that an inflammatory process in the synovial membrane triggers the generation of oxidative and nitrosative acting substances which can lead to a further degradation of the articular cartilage. Based on correlations between the observed degree of inflammation and investigated biomarkers, especially 8-isoprostane F2α seems to be a novel candidate biomarker for OA. However, due to the finding that also both control groups showed increased concentrations of selected biomarkers, future studies have to validate the diagnostic potential of these biomarkers in OA and in related conditions of the knee joint.

scholarly journals Pleiotropic Effects of the P5-Type ATPase SpfA on Stress Response Networks Contribute to Virulence in the Pathogenic Mold Aspergillus fumigatus

mBio ◽  
2021 ◽  
Author(s):  
José P. Guirao-Abad ◽  
Martin Weichert ◽  
Ginés Luengo-Gil ◽  
Sarah Sze Wah Wong ◽  
Vishukumar Aimanianda ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Resistance ◽  
Secretory Pathway ◽  
Pathogenic Fungi ◽  
Antifungal Drugs ◽  
Gene Encoding ◽  
Content Type ◽  
Downstream Target ◽  
P Type ◽  
Er Homeostasis

The fungal UPR is an adaptive signaling pathway in the ER that buffers fluctuations in ER stress but also serves as a virulence regulatory hub in species of pathogenic fungi that rely on secretory pathway homeostasis for pathogenicity. This study demonstrates that the gene encoding the ER-localized P5-type ATPase SpfA is a downstream target of the UPR in the pathogenic mold A. fumigatus and that it works together with a second ER-localized P-type ATPase, SrcA, to support ER homeostasis, oxidative stress resistance, susceptibility to antifungal drugs, and virulence of A. fumigatus .

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