scholarly journals The Staphylococcal Ferritins Are Differentially Regulated in Response to Iron and Manganese and via PerR and Fur

2004 ◽  
Vol 72 (2) ◽  
pp. 972-979 ◽  
Author(s):  
Julie A. Morrissey ◽  
Alan Cockayne ◽  
Kirsty Brummell ◽  
Paul Williams
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Staphylococcus Epidermidis ◽  
Oxidative Stress Response ◽  
Metal Availability ◽  
Wild Type ◽  
Additional Level ◽  
Alkyl Hydroperoxidase ◽  
Iron And Manganese

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis ferritin (FtnA and SefA, respectively) homologues are antigenic and highly conserved. A previous study showed that ftnA is a component of the S. aureus PerR regulon with its transcription induced by elevated iron and repressed by PerR, which functions as a manganese-dependent transcriptional repressor. We have further investigated the role of iron and Fur in the regulation of PerR regulon genes ftnA (ferritin), ahpC (alkyl-hydroperoxidase), and mrgA (Dps homologue) and shown that iron has a major role in the regulation of the PerR regulon and hence the oxidative stress response, since in the presence of both iron and manganese, transcription of PerR regulon genes is induced above the repressed levels observed with manganese alone. Furthermore the PerR regulon genes are differentially regulated by metal availability and Fur. First, there is an additional level of PerR-independent regulation of ftnA under low-iron conditions which is not observed with ahpC and mrgA. Second, there is a differential response of these genes to Fur as ftnA expression is constitutive in a fur mutant, while ahpC expression is constitutive under low-Fe/Mn conditions but some repression of ahpC still occurs in the presence of manganese, whereas mrgA expression is still repressed in the fur mutant as in wild-type S. aureus, although there is a decrease in the overall level of mrgA transcription. These studies have also shown that FtnA expression is regulated by growth phase, but maximal transcription of ftnA differs dependent on the growth medium. Moreover, there are significant regulatory differences between the S. aureus and S. epidermidis ferritins, as sefA expression in contrast to that of ftnA is derepressed under low-Fe/Mn ion conditions.

scholarly journals The OxyR homologue in Tannerella forsythia regulates expression of oxidative stress responses and biofilm formation

Microbiology ◽  
2009 ◽  
Vol 155 (6) ◽  
pp. 1912-1922 ◽  
Author(s):  
Kiyonobu Honma ◽  
Elina Mishima ◽  
Satoru Inagaki ◽  
Ashu Sharma
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Oxidative Stress Response ◽  
Wild Type ◽  
Tannerella Forsythia ◽  
Antioxidant Genes

Tannerella forsythia is an anaerobic periodontal pathogen that encounters constant oxidative stress in the human oral cavity due to exposure to air and reactive oxidative species from coexisting dental plaque bacteria as well as leukocytes. In this study, we sought to characterize a T. forsythia ORF with close similarity to bacterial oxidative stress response sensor protein OxyR. To analyse the role of this OxyR homologue, a gene deletion mutant was constructed and characterized. Aerotolerance, survival after hydrogen peroxide challenge and transcription levels of known bacterial antioxidant genes were then determined. Since an association between oxidative stress and biofilm formation has been observed in bacterial systems, we also investigated the role of the OxyR protein in biofilm development by T. forsythia. Our results showed that aerotolerance, sensitivity to peroxide challenge and the expression of oxidative stress response genes were significantly reduced in the mutant as compared with the wild-type strain. Moreover, the results of biofilm analyses showed that, as compared with the wild-type strain, the oxyR mutant showed significantly less autoaggregation and a reduced ability to form mixed biofilms with Fusobacterium nucleatum. In conclusion, a gene annotated in the T. forsythia genome as an oxyR homologue was characterized. Our studies showed that the oxyR homologue in T. forsythia constitutively activates antioxidant genes involved in resistance to peroxides as well as oxygen stress (aerotolerance). In addition, the oxyR deletion attenuates biofilm formation in T. forsythia.

scholarly journals Syntaxin-17-Dependent Mitochondrial Dynamics is Essential for Protection Against Oxidative-Stress-Induced Apoptosis

Antioxidants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 522 ◽  
Author(s):  
Wang ◽  
Xiao ◽  
Huang ◽  
Liu
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Autophagic Flux ◽  
Wild Type ◽  
Dual Roles ◽  
Defective Mutant ◽  
U2os Cells ◽  
Induced Apoptosis

In this study, cell death induced by the oxidant tert-butylhydroperoxide (tBH) was observed in U2OS cells; this phenotype was rescued by Syntaxin 17 (STX17) knockout (KO) but the mechanism is unknown. STX17 plays dual roles in autophagosome–lysosome fusion and mitochondrial fission. However, the contribution of the two functions of STX17 to apoptosis has not been extensively studied. Here, we sought to dissect the dual roles of STX17 in oxidative-stress-induced apoptosis by taking advantage of STX17 knockout cells and an autophagosome–lysosome fusion defective mutant of STX17. We generated STX17 knockout U2OS cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and the STX17 knockout cells were reconstituted with wild-type STX17 and its autophagosome–lysosome fusion defective mutant. Autophagy was assessed by autophagic flux assay, Monomer red fluorescent protein (mRFP)–GFP–LC3 assay and protease protection assay. Golgi, endoplasmic reticulum (ER)/ER–Golgi intermediate compartment (ERGIC) and mitochondrial dynamics were examined by staining the different indicator proteins. Apoptosis was evaluated by caspase cleavage assay. The general reactive oxygen species (ROS) were detected by flow cytometry. In STX17 complete knockout cells, sealed autophagosomes were efficiently formed but their fusion with lysosomes was less defective. The fusion defect was rescued by wild-type STX17 but not the autophagosome–lysosome fusion defective mutant. No obvious defects in Golgi, ERGIC or ER dynamics were observed. Mitochondria were significantly elongated, supporting a role of STX17 in mitochondria fission and the elongation caused by STX17 KO was reversed by the autophagosome–lysosome fusion defective mutant. The clearance of protein aggregation was compromised, correlating with the autophagy defect but not with mitochondrial dynamics. This study revealed a mixed role of STX17 in autophagy, mitochondrial dynamics and oxidative stress response. STX17 knockout cells were highly resistant to oxidative stress, largely due to the function of STX17 in mitochondrial fission rather than autophagy.

scholarly journals The Phosphoarginine Phosphatase PtpB from Staphylococcus aureus Is Involved in Bacterial Stress Adaptation during Infection

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 645
Author(s):  
Mohamed Ibrahem Elhawy ◽  
Sylvaine Huc-Brandt ◽  
Linda Pätzold ◽  
Laila Gannoun-Zaki ◽  
Ahmed Mohamed Mostafa Abdrabou ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Treatment Strategies ◽  
Physiological Role ◽  
Aureus Strain ◽  
Stress Adaptation ◽  
Cellular Mechanisms ◽  
Host Interaction ◽  
Liver And Kidney

Staphylococcus aureus continues to be a public health threat, especially in hospital settings. Studies aimed at deciphering the molecular and cellular mechanisms that underlie pathogenesis, host adaptation, and virulence are required to develop effective treatment strategies. Numerous host-pathogen interactions were found to be dependent on phosphatases-mediated regulation. This study focused on the analysis of the role of the low-molecular weight phosphatase PtpB, in particular, during infection. Deletion of ptpB in S. aureus strain SA564 significantly reduced the capacity of the mutant to withstand intracellular killing by THP-1 macrophages. When injected into normoglycemic C57BL/6 mice, the SA564 ΔptpB mutant displayed markedly reduced bacterial loads in liver and kidney tissues in a murine S. aureus abscess model when compared to the wild type. We also observed that PtpB phosphatase-activity was sensitive to oxidative stress. Our quantitative transcript analyses revealed that PtpB affects the transcription of various genes involved in oxidative stress adaptation and infectivity. Thus, this study disclosed first insights into the physiological role of PtpB during host interaction allowing us to link phosphatase-dependent regulation to oxidative bacterial stress adaptation during infection.

scholarly journals Influence of Metal-Resistant Staphylococcus aureus Strain K1 on the Alleviation of Chromium Stress in Wheat

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1354 ◽  
Author(s):  
Fanrong Zeng ◽  
Munazza Zahoor ◽  
Muhammad Waseem ◽  
Alia Anayat ◽  
Muhammad Rizwan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Anthropogenic Activities ◽  
Toxic Metal ◽  
Triticum Aestivum L ◽  
Aureus Strain ◽  
Peat Moss ◽  
Cr Toxicity ◽  
Living Organisms

Chromium (Cr) is recognized as a toxic metal that has detrimental effects on living organisms; notably, it is discharged into soil by various industries as a result of anthropogenic activities. Microbe-assisted phytoremediation is one of the most emergent and environmentally friendly methods used for the detoxification of pollutants. In this study, the alleviative role of Staphylococcus aureus strain K1 was evaluated in wheat (Triticum aestivum L.) under Cr stress. For this, various Cr concentrations (0, 25, 50 and 100 mg·kg−1) with and without peat-moss-based bacterial inoculum were applied in the soil. Results depicted that Cr stress reduced the plants’ growth by causing oxidative stress in the absence of S. aureus K1 inoculation. However, the application of S. aureus K1 regulated the plants’ growth and antioxidant enzymatic activities by reducing oxidative stress and Cr toxicity through conversion of Cr6+ to Cr3+. The Cr6+ uptake by wheat was significantly reduced in the S. aureus K1 inoculated plants. It can be concluded that the application of S. aureus K1 could be an effective approach to alleviate the Cr toxicity in wheat and probably in other cereals grown under Cr stress.

scholarly journals Causal Role of Single Nucleotide Polymorphisms within themprFGene of Staphylococcus aureus in Daptomycin Resistance

2013 ◽  
Vol 57 (11) ◽  
pp. 5658-5664 ◽  
Author(s):  
Soo-Jin Yang ◽  
Nagendra N. Mishra ◽  
Aileen Rubio ◽  
Arnold S. Bayer
Keyword(s):  
Staphylococcus Aureus ◽  
Single Nucleotide Polymorphisms ◽  
Point Mutations ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Single Nucleotide ◽  
Content Type ◽  
Reading Frame ◽  
A Charge

ABSTRACTSingle nucleotide polymorphisms (SNPs) within themprFopen reading frame (ORF) have been commonly observed in daptomycin-resistant (DAPr)Staphylococcus aureusstrains. Such SNPs are usually associated with a gain-in-function phenotype, in terms of either increased synthesis or enhanced translocation (flipping) of lysyl-phosphatidylglycerol (L-PG). However, it is unclear if suchmprFSNPs are causal in DAPrstrains or are merely a biomarker for this phenotype. In this study, we used an isogenic set ofS. aureusstrains: (i) Newman, (ii) its isogenic ΔmprFmutant, and (iii) several intransplasmid complementation constructs, expressing either a wild-type or point-mutated form of themprFORF cloned from two isogenic DAP-susceptible (DAPs)-DAPrstrain pairs (616-701 and MRSA11/11-REF2145). Complementation of the ΔmprFstrain with singly point-mutatedmprFgenes (mprFS295LormprFT345A) revealed that (i) individual and distinct point mutations within themprFORF can recapitulate phenotypes observed in donor strains (i.e., changes in DAP MICs, positive surface charge, and cell membrane phospholipid profiles) and (ii) these gain-in-function SNPs (i.e., enhanced L-PG synthesis) likely promote reduced DAP binding toS. aureusby a charge repulsion mechanism. Thus, for these two DAPrstrains, the definedmprFSNPs appear to be causally related to this phenotype.

scholarly journals Role of ALADIN in Human Adrenocortical Cells for Oxidative Stress Response and Steroidogenesis

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0124582 ◽  
Author(s):  
Ramona Jühlen ◽  
Jan Idkowiak ◽  
Angela E. Taylor ◽  
Barbara Kind ◽  
Wiebke Arlt ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Adrenocortical Cells

The role of CSA and CSB protein in the oxidative stress response

2013 ◽  
Vol 134 (5-6) ◽  
pp. 261-269 ◽  
Author(s):  
Mariarosaria D’Errico ◽  
Barbara Pascucci ◽  
Egidio Iorio ◽  
Bennett Van Houten ◽  
Eugenia Dogliotti
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Oxidative Stress Response

scholarly journals Enhanced production of exopolysaccharide matrix and biofilm by a menadione-auxotrophic Staphylococcus aureus small-colony variant

2010 ◽  
Vol 59 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Rachna Singh ◽  
Pallab Ray ◽  
Anindita Das ◽  
Meera Sharma
Keyword(s):  
Staphylococcus Aureus ◽  
Tricarboxylic Acid Cycle ◽  
Surface Hydrophobicity ◽  
Tricarboxylic Acid ◽  
Polysaccharide Intercellular Adhesin ◽  
Wild Type ◽  
Small Colony Variant ◽  
Enhanced Production ◽  
Small Colony

The role of Staphylococcus aureus small-colony variants (SCVs) in the pathogenesis of biofilm-associated infections remains unclear. This study investigated the mechanism behind increased biofilm-forming potential of a menadione-auxotrophic Staphylococcus aureus SCV compared with the wild-type parental strain, as recently reported by our laboratory. SCVs displayed an autoaggregative phenotype, with a greater amount of polysaccharide intercellular adhesin (PIA), significantly reduced tricarboxylic acid cycle activity and a decreased susceptibility to aminoglycosides and cell-wall inhibitors compared with wild-type. The biofilms formed by the SCV were highly structured, consisting of large microcolonies separated by channels, and contained more biomass as well as significantly more PIA than wild-type biofilms. The surface hydrophobicity of the two phenotypes was similar. Thus, the autoaggregation and increased biofilm-forming capacity of menadione-auxotrophic Staphylococcus aureus SCVs in this study was related to the enhanced production of PIA in these variants.

Sign in / Sign up

Export Citation Format

Share Document