In Staphylococcus aureus, Fur Is an Interactive Regulator with PerR, Contributes to Virulence, and Is Necessary for Oxidative Stress Resistance through Positive Regulation of Catalase and Iron Homeostasis

ABSTRACT The Staphylococcus aureus genome encodes three ferric uptake repressor (Fur) homologues: Fur, PerR, and Zur. To determine the exact role of Fur in S. aureus, we inactivated thefur gene by allelic replacement using a tetracycline resistance cassette, creating strain MJH010 (fur). The mutant had a growth defect in rich medium, and this defect was exacerbated in metal-depleted CL medium. This growth defect was partially suppressed by manganous ion, a metal ion with known antioxidant properties. This suggests that the fur mutation leads to an oxidative stress condition. Indeed, MJH010 (fur) has reduced levels of catalase activity resulting from decreased katA transcription. Using akatA-lacZ fusion we have determined that Fur functions, either directly or indirectly, as an iron-dependent positive regulator of katA expression. Transcription of katA is coregulated by Fur and PerR, since in MJH010 (fur) transcription was still repressed by manganese while transcription in MJH201 (fur perR) was unresponsive to the presence of iron or manganese. Siderophore biosynthesis was repressed by iron in 8325-4 (wild-type) but in MJH010 (fur) was constitutive. A number of putative Fur-regulated genes were identified in the incomplete genome databases using known S. aureus Fur box sequences. Of those tested, the sstABCD andsirABC operons and the fhuD2 andorf4 genes were found to have Fur-regulated expression. MJH010 (fur) was attenuated (P < 0.04) in a murine skin abscess model of infection, as was double-mutant MJH201 (fur perR) (P < 0.03). This demonstrates the importance in vivo of iron homeostasis and oxidative stress resistance regulation in S. aureus.

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Catalase (KatA) and Alkyl Hydroperoxide Reductase (AhpC) Have Compensatory Roles in Peroxide Stress Resistance and Are Required for Survival, Persistence, and Nasal Colonization in Staphylococcus aureus

Journal of Bacteriology ◽

10.1128/jb.01524-06 ◽

2006 ◽

Vol 189 (3) ◽

pp. 1025-1035 ◽

Cited By ~ 161

Author(s):

Kate Cosgrove ◽

Graham Coutts ◽

Ing-Marie Jonsson ◽

Andrej Tarkowski ◽

John F. Kokai-Kun ◽

...

Keyword(s):

Oxidative Stress ◽

Staphylococcus Aureus ◽

Stress Resistance ◽

Catalase Activity ◽

Metal Ion ◽

Hospital Environment ◽

Growth Defect ◽

Nasal Colonization ◽

Oxidative Stress Resistance ◽

Metal Ion Homeostasis

ABSTRACT Oxidative-stress resistance in Staphylococcus aureus is linked to metal ion homeostasis via several interacting regulators. In particular, PerR controls the expression of a regulon of genes, many of which encode antioxidants. Two PerR regulon members, ahpC (alkylhydroperoxide reductase) and katA (catalase), show compensatory regulation, with independent and linked functions. An ahpC mutation leads to increased H2O2 resistance due to greater katA expression via relief of PerR repression. Moreover, AhpC provides residual catalase activity present in a katA mutant. Mutation of both katA and ahpC leads to a severe growth defect under aerobic conditions in defined media (attributable to lack of catalase activity). This results in the inability to scavenge exogenous or endogenously produced H2O2, resulting in accumulation of H2O2 in the medium. This leads to DNA damage, the likely cause of the growth defect. Surprisingly, the katA ahpC mutant is not attenuated in two independent models of infection, which implies reduced oxygen availability during infection. In contrast, both AhpC and KatA are required for environmental persistence (desiccation) and nasal colonization. Thus, oxidative-stress resistance is an important factor in the ability of S. aureus to persist in the hospital environment and so contribute to the spread of human disease.

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PerR Controls Oxidative Stress Resistance and Iron Storage Proteins and Is Required for Virulence in Staphylococcus aureus

Infection and Immunity ◽

10.1128/iai.69.6.3744-3754.2001 ◽

2001 ◽

Vol 69 (6) ◽

pp. 3744-3754 ◽

Cited By ~ 231

Author(s):

Malcolm J. Horsburgh ◽

Mark O. Clements ◽

Howard Crossley ◽

Eileen Ingham ◽

Simon J. Foster

Keyword(s):

Oxidative Stress ◽

Staphylococcus Aureus ◽

Stress Resistance ◽

Iron Homeostasis ◽

Storage Proteins ◽

Iron Storage ◽

Oxidative Stress Resistance ◽

Genes Encoding ◽

Starvation Survival ◽

Iron Storage Proteins

ABSTRACT The Staphylococcus aureus genome encodes three ferric uptake regulator (Fur) homologues: Fur, PerR, and Zur. To determine the exact role of PerR, we inactivated the gene by allelic replacement using a kanamycin cassette, creating strain MJH001 (perR). PerR was found to control transcription of the genes encoding the oxidative stress resistance proteins catalase (KatA), alkyl hydroperoxide reductase (AhpCF), bacterioferritin comigratory protein (Bcp), and thioredoxin reductase (TrxB). Furthermore, PerR regulates transcription of the genes encoding the iron storage proteins ferritin (Ftn) and the ferritin-like Dps homologue, MrgA. Transcription of perR was autoregulated, and PerR repressed transcription of the iron homeostasis regulator Fur, which is a positive regulator of catalase expression. PerR functions as a manganese-dependent, transcriptional repressor of the identified regulon. Elevated iron concentrations produced induction of the PerR regulon. PerR may act as a peroxide sensor, since addition of external hydrogen peroxide to 8325-4 (wild type) resulted in increased transcription of most of the PerR regulon, except forfur and perR itself. The PerR-regulatedkatA gene encodes the sole catalase of S. aureus, which is an important starvation survival determinant but is surprisingly not required for pathogenicity in a murine skin abscess model of infection. In contrast, PerR is not necessary for starvation survival but is required for full virulence (P < 0.005) in this model of infection. PerR ofS. aureus may act as a redox sentinel protein during infection, analogous to the in vitro activities of OxyR and PerR ofEscherichia coli and Bacillus subtilis, respectively. However, it differs in its response to the metal balance within the cell and has the added capability of regulating iron uptake and storage.

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Intersection of phosphate transport, oxidative stress and TOR signalling inCandida albicansvirulence

10.1101/317933 ◽

2018 ◽

Author(s):

Ning-Ning Liu ◽

Priya Uppuluri ◽

Achille Broggi ◽

Angelique Besold ◽

Kicki Ryman ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Management ◽

Stress Resistance ◽

Ex Vivo ◽

Growth Defect ◽

Invasive Infection ◽

Wild Type ◽

Oxidative Stress Resistance ◽

Ros Accumulation

AbstractPhosphate is an essential macronutrient required for cell growth and division. Pho84 is the major high-affinity cell-surface phosphate importer ofSaccharomyces cerevisiaeand a crucial element in the phosphate homeostatic system of this model yeast. We found that loss ofCandida albicansPho84 attenuated virulence inDrosophilaand murine oropharyngeal and disseminated models of invasive infection, and conferred hypersensitivity to neutrophil killing. Susceptibility of cells lacking Pho84 to neutrophil attack depended on reactive oxygen species (ROS):pho84-/-cells were no more susceptible than wild typeC. albicansto neutrophils from a patient with chronic granulomatous disease, or to those whose oxidative burst was pharmacologically inhibited or neutralized.pho84-/-mutants hyperactivated oxidative stress signalling. They accumulated intracellular ROS in the absence of extrinsic oxidative stress, in high as well as low ambient phosphate conditions. ROS accumulation correlated with diminished levels of the unique superoxide dismutase Sod3 inpho84-/-cells, whileSOD3overexpression from a conditional promoter substantially restored these cells’ oxidative stress resistance in vitro. Repression ofSOD3expression sharply increased their oxidative stress hypersensitivity. Neither of these oxidative stress management effects of manipulatingSOD3transcription was observed inPHO84wild type cells. Sod3 levels were not the only factor driving oxidative stress effects onpho84-/-cells, though, because overexpressingSOD3did not ameliorate these cells’ hypersensitivity to neutrophil killing ex vivo, indicating Pho84 has further roles in oxidative stress resistance and virulence. Measurement of cellular metal concentrations demonstrated that diminished Sod3 expression was not due to decreased import of its metal cofactor manganese, as predicted from the function ofS. cerevisiaePho84 as a low-affinity manganese transporter. Instead of a role of Pho84 in metal transport, we found its role in TORC1 activation to impact oxidative stress management: overexpression of the TORC1-activating GTPase Gtr1 relieved the Sod3 deficit and ROS excess inpho84-/-null mutant cells, though it did not suppress their hypersensitivity to neutrophil killing or hyphal growth defect. Pharmacologic inhibition of Pho84 by small molecules including the FDA-approved drug foscarnet also induced ROS accumulation. Inhibiting Pho84 could hence support host defenses by sensitizingC. albicansto oxidative stress.

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YjbH regulates virulence genes expression and oxidative stress resistance in Staphylococcus aureus

Virulence ◽

10.1080/21505594.2021.1875683 ◽

2021 ◽

Vol 12 (1) ◽

pp. 470-480

Author(s):

Atmika Paudel ◽

Suresh Panthee ◽

Hiroshi Hamamoto ◽

Tom Grunert ◽

Kazuhisa Sekimizu

Keyword(s):

Oxidative Stress ◽

Staphylococcus Aureus ◽

Stress Resistance ◽

Virulence Genes ◽

Oxidative Stress Resistance ◽

Genes Expression ◽

And Oxidative Stress

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Polygonum multiflorum Extract Exerts Antioxidative Effects and Increases Life Span and Stress Resistance in the Model Organism Caenorhabditis elegans via DAF-16 and SIR-2.1

Plants ◽

10.3390/plants7030060 ◽

2018 ◽

Vol 7 (3) ◽

pp. 60 ◽

Cited By ~ 9

Author(s):

Christina Saier ◽

Christian Büchter ◽

Karoline Koch ◽

Wim Wätjen

Keyword(s):

Oxidative Stress ◽

Caenorhabditis Elegans ◽

Life Span ◽

Stress Resistance ◽

Model Organism ◽

Aging Effects ◽

Polygonum Multiflorum ◽

Oxidative Stress Resistance ◽

Antioxidative Effects

Extracts of the Chinese plant Polygonum multiflorum (PME) are used for medicinal purposes as well as food supplement due to anti-aging effects. Despite of the common use of these food supplements, experimental data on physiological effects of PME and its underlying molecular mechanisms in vivo are limited. We used the model organism Caenorhabditis elegans to analyze anti-aging-effects of PME in vivo (life span, lipofuscin accumulation, oxidative stress resistance, thermal stress resistance) as well as the molecular signaling pathways involved. The effects of PME were examined in wildtype animals and mutants defective in the sirtuin-homologue SIR-2.1 (VC199) and the FOXO-homologue DAF-16 (CF1038). PME possesses antioxidative effects in vivo and increases oxidative stress resistance of the nematodes. While the accumulation of lipofuscin is only slightly decreased, PME causes a significant elongation (18.6%) of mean life span. DAF-16 is essential for the reduction of thermally induced ROS accumulation, while the resistance against paraquat-induced oxidative stress is dependent on SIR-2.1. For the extension of the life span, both DAF-16 and SIR-2.1 are needed. We demonstrate that PME exerts protective effects in C. elegans via modulation of distinct intracellular pathways.

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Cdk8 and Ssn801 Regulate Oxidative Stress Resistance and Virulence inCryptococcus neoformans

mBio ◽

10.1128/mbio.02818-18 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 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.

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