scholarly journals Contribution of a PerR-like regulator to the oxidative-stress response and virulence of Enterococcus faecalis

Microbiology ◽  
2005 ◽  
Vol 151 (12) ◽  
pp. 3997-4004 ◽  
Author(s):  
Nicolas Verneuil ◽  
Alain Rincé ◽  
Maurizio Sanguinetti ◽  
Brunella Posteraro ◽  
Giovanni Fadda ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Enterococcus Faecalis ◽  
Oxidative Stress Response ◽  
Homologous Gene ◽  
Wild Type ◽  
Real Time Quantitative Pcr ◽  
Phenotype Analysis ◽  
In The Wild ◽  
Peritonitis Model

PerR is one of the most important transcriptional regulators involved in the oxidative-stress response in Bacillus subtilis. Here, the homologous gene in Enterococcus faecalis, ranked among the leading causes of nosocomial infection, was characterized and analysed. Phenotype analysis showed that the perR mutant was significantly more resistant to H2O2 challenge (P<0·05). Expression of eight genes with potential roles in the oxidative-stress response was determined in the wild-type and perR-mutant strains by real-time quantitative PCR. Surprisingly, low quantitative differences in the transcriptional activity of these genes in the mutant versus wild-type were observed. Likewise, this locus was not involved in survival within murine macrophages, but in the mouse peritonitis model, the perR mutant appeared less lethal than the JH2-2 wild-type strain. The combined results show that PerR affects E. faecalis virulence and that its implication in the transcriptional regulation in this bacterium deviates from the B. subtilis model.

scholarly journals Transcriptional Response of Leptospira interrogans to Iron Limitation and Characterization of a PerR Homolog

2010 ◽  
Vol 78 (11) ◽  
pp. 4850-4859 ◽  
Author(s):  
Miranda Lo ◽  
Gerald L. Murray ◽  
Chen Ai Khoo ◽  
David A. Haake ◽  
Richard L. Zuerner ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Iron Homeostasis ◽  
Storage Proteins ◽  
Iron Acquisition ◽  
Bacterial Species ◽  
Transcriptional Response ◽  
Oxidative Stress Response ◽  
Wild Type ◽  
In The Wild

ABSTRACT Leptospirosis is a globally significant zoonosis caused by Leptospira spp. Iron is essential for growth of most bacterial species. Since iron availability is low in the host, pathogens have evolved complex iron acquisition mechanisms to survive and establish infection. In many bacteria, expression of iron uptake and storage proteins is regulated by Fur. L. interrogans encodes four predicted Fur homologs; we have constructed a mutation in one of these, la1857. We conducted microarray analysis to identify iron-responsive genes and to study the effects of la1857 mutation on gene expression. Under iron-limiting conditions, 43 genes were upregulated and 49 genes were downregulated in the wild type. Genes encoding proteins with predicted involvement in inorganic ion transport and metabolism (including TonB-dependent proteins and outer membrane transport proteins) were overrepresented in the upregulated list, while 54% of differentially expressed genes had no known function. There were 16 upregulated genes of unknown function which are absent from the saprophyte L. biflexa and which therefore may encode virulence-associated factors. Expression of iron-responsive genes was not significantly affected by mutagenesis of la1857, indicating that LA1857 is not a global regulator of iron homeostasis. Upregulation of heme biosynthetic genes and a putative catalase in the mutant suggested that LA1857 is more similar to PerR, a regulator of the oxidative stress response. Indeed, the la1857 mutant was more resistant to peroxide stress than the wild type. Our results provide insights into the role of iron in leptospiral metabolism and regulation of the oxidative stress response, including genes likely to be important for virulence.

scholarly journals Virulence of Streptococcus pneumoniae: PsaA Mutants Are Hypersensitive to Oxidative Stress

2002 ◽  
Vol 70 (3) ◽  
pp. 1635-1639 ◽  
Author(s):  
Hsing-Ju Tseng ◽  
Alastair G. McEwan ◽  
James C. Paton ◽  
Michael P. Jennings
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Pneumoniae ◽  
Stress Response ◽  
Nadh Oxidase ◽  
Redox Homeostasis ◽  
Oxidative Stress Response ◽  
Wild Type ◽  
Regulation Of Expression ◽  
Altered Expression ◽  
Transport Complex

ABSTRACT psaA encodes a 37-kDa pneumococcal lipoprotein which is part of an ABC Mn(II) transport complex. Streptococcus pneumoniae D39 psaA mutants have previously been shown to be significantly less virulent than wild-type D39, but the mechanism underlying the attenuation has not been resolved. In this study, we have shown that psaA and psaD mutants are highly sensitive to oxidative stress, i.e., to superoxide and hydrogen peroxide, which might explain why they are less virulent than the wild-type strain. Our investigations revealed altered expression of the key oxidative-stress response enzymes superoxide dismutase and NADH oxidase in psaA and psaD mutants, suggesting that PsaA and PsaD may play important roles in the regulation of expression of oxidative-stress response enzymes and intracellular redox homeostasis.

scholarly journals Calcium-binding protein 39 facilitates molecular interaction between Ste20p proline alanine-rich kinase and oxidative stress response 1 monomers

2012 ◽  
Vol 303 (11) ◽  
pp. C1198-C1205 ◽  
Author(s):  
José Ponce-Coria ◽  
Kenneth B. Gagnon ◽  
Eric Delpire
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Calcium Binding ◽  
Binding Protein ◽  
Oxidative Stress Response ◽  
Calcium Binding Protein ◽  
Domain Swapping ◽  
Xenopus Laevis Oocytes ◽  
Wild Type ◽  
Kinase Activation

X-ray crystallography of the catalytic domain of oxidative stress response 1 (OSR1) has provided evidence for dimerization and domain swapping. However, the functional significance of dimer formation or domain swapping has yet to be addressed. In this study, we used nine glutamine residues to link the carboxyl end of one SPAK (related Ste20 kinase) monomer to the amino end of another SPAK monomer to assess the role of kinase monomers versus dimers in Na-K-2Cl cotransporter 1 (NKCC1) activation. Transport studies in Xenopus laevis oocytes show that forcing dimerization of two wild-type SPAK molecules results in cotransporter activation when calcium-binding protein 39 (Cab39) is coexpressed, indicating that the presence of Cab39 can bypass the upstream phosphorylation requirement of SPAK normally associated with kinase activation. We determined that monomers are the functional units of the kinase as concatamers consisting of an active and various inactive monomers were still functional. Furthermore, we found that two different nonfunctional SPAK mutants could be linked together in a concatamer and activated, presumably by domain swapping, indicating that dimerization and domain swapping are both important components of kinase activation. Finally, we demonstrate rescue of a nonfunctional SPAK mutant by domain swapping with wild-type OSR1, indicating that heterodimers of the two Ste20-related kinases are possible and therefore potentially relevant to the regulation of NKCC1 activity.

scholarly journals Bach1Deficiency and Accompanying Overexpression of Heme Oxygenase-1 Do Not Influence Aging or Tumorigenesis in Mice

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Kazushige Ota ◽  
Andrey Brydun ◽  
Ari Itoh-Nakadai ◽  
Jiying Sun ◽  
Kazuhiko Igarashi
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Heme Oxygenase ◽  
Transcriptional Activity ◽  
Oxidative Stress Response ◽  
Acute Injury ◽  
Heme Oxygenase 1 ◽  
Wild Type ◽  
Environmental Perturbations ◽  
Deficient Mice

Oxidative stress contributes to both aging and tumorigenesis. The transcription factor Bach1, a regulator of oxidative stress response, augments oxidative stress by repressing the expression of heme oxygenase-1 (HO-1) gene (Hmox1) and suppresses oxidative stress-induced cellular senescence by restricting the p53 transcriptional activity. Here we investigated the lifelong effects ofBach1deficiency on mice.Bach1-deficient mice showed longevity similar to wild-type mice. Although HO-1 was upregulated in the cells ofBach1-deficient animals, the levels of ROS inBach1-deficient HSCs were comparable to those in wild-type cells.Bach1−/−;p53−/−mice succumbed to spontaneous cancers as frequently asp53-deficient mice.Bach1deficiency significantly altered transcriptome in the liver of the young mice, which surprisingly became similar to that of wild-type mice during the course of aging. The transcriptome adaptation toBach1deficiency may reflect how oxidative stress response is tuned upon genetic and environmental perturbations. We concluded thatBach1deficiency and accompanying overexpression of HO-1 did not influence aging or p53 deficiency-driven tumorigenesis. Our results suggest that it is useful to target Bach1 for acute injury responses without inducing any apparent deteriorative effect.

scholarly journals Xrp1 and Irbp18 trigger a feed-forward loop of proteotoxic stress to induce the loser status

PLoS Genetics ◽  
2021 ◽  
Vol 17 (12) ◽  
pp. e1009946
Author(s):  
Paul F. Langton ◽  
Michael E. Baumgartner ◽  
Remi Logeay ◽  
Eugenia Piddini
Keyword(s):  
Oxidative Stress ◽  
Transcription Factors ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Wild Type ◽  
Cell Competition ◽  
Feed Forward ◽  
Feed Forward Loop ◽  
Proteotoxic Stress

Cell competition induces the elimination of less-fit “loser” cells by fitter “winner” cells. In Drosophila, cells heterozygous mutant in ribosome genes, Rp/+, known as Minutes, are outcompeted by wild-type cells. Rp/+ cells display proteotoxic stress and the oxidative stress response, which drive the loser status. Minute cell competition also requires the transcription factors Irbp18 and Xrp1, but how these contribute to the loser status is partially understood. Here we provide evidence that initial proteotoxic stress in RpS3/+ cells is Xrp1-independent. However, Xrp1 is sufficient to induce proteotoxic stress in otherwise wild-type cells and is necessary for the high levels of proteotoxic stress found in RpS3/+ cells. Surprisingly, Xrp1 is also induced downstream of proteotoxic stress, and is required for the competitive elimination of cells suffering from proteotoxic stress or overexpressing Nrf2. Our data suggests that a feed-forward loop between Xrp1, proteotoxic stress, and Nrf2 drives Minute cells to become losers.

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 The Transcription Factor Sfp1 Regulates the Oxidative Stress Response in Candida albicans

2019 ◽  
Vol 7 (5) ◽  
pp. 131 ◽  
Author(s):  
Shao-Yu Lee ◽  
Hsueh-Fen Chen ◽  
Ying-Chieh Yeh ◽  
Yao-Peng Xue ◽  
Chung-Yu Lan
Keyword(s):  
Oxidative Stress ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Antifungal Drugs ◽  
Wild Type ◽  
Antioxidant Genes ◽  
Type C ◽  
Macrophage Killing

Candida albicans is a commensal that inhabits the skin and mucous membranes of humans. Because of the increasing immunocompromised population and the limited classes of antifungal drugs available, C. albicans has emerged as an important opportunistic pathogen with high mortality rates. During infection and therapy, C. albicans frequently encounters immune cells and antifungal drugs, many of which exert their antimicrobial activity by inducing the production of reactive oxygen species (ROS). Therefore, antioxidative capacity is important for the survival and pathogenesis of C. albicans. In this study, we characterized the roles of the zinc finger transcription factor Sfp1 in the oxidative stress response against C. albicans. A sfp1-deleted mutant was more resistant to oxidants and macrophage killing than wild-type C. albicans and processed an active oxidative stress response with the phosphorylation of the mitogen-activated protein kinase (MAPK) Hog1 and high CAP1 expression. Moreover, the sfp1-deleted mutant exhibited high expression levels of antioxidant genes in response to oxidative stress, resulting in a higher total antioxidant capacity, glutathione content, and glutathione peroxidase and superoxide dismutase enzyme activity than the wild-type C. albicans. Finally, the sfp1-deleted mutant was resistant to macrophage killing and ROS-generating antifungal drugs. Together, our findings provide a new understanding of the complex regulatory machinery in the C. albicans oxidative stress response.

Relationships between Oxidative Stress Response and Virulence in Enterococcus faecalis

2007 ◽  
Vol 13 (1-3) ◽  
pp. 140-146 ◽  
Author(s):  
Eliette Riboulet ◽  
Nicolas Verneuil ◽  
Stéphanie La Carbona ◽  
Nicolas Sauvageot ◽  
Yanick Auffray ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Enterococcus Faecalis ◽  
Oxidative Stress Response

scholarly journals Small RNA GcvB Regulates Oxidative Stress Response of Escherichia coli

Antioxidants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1774
Author(s):  
Xian Ju ◽  
Xingxing Fang ◽  
Yunzhu Xiao ◽  
Bingyu Li ◽  
Ruoping Shi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Small Rna ◽  
Minimal Medium ◽  
Oxidative Stress Response ◽  
Wild Type ◽  
Knockout Strain ◽  
Additional Layer ◽  
K 12

Small non-translated regulatory RNAs control plenty of bacterial vital activities. The small RNA GcvB has been extensively studied, indicating the multifaceted roles of GcvB beyond amino acid metabolism. However, few reported GcvB-dependent regulation in minimal medium. Here, by applying a high-resolution RNA-seq assay, we compared the transcriptomes of a wild-type Escherichia coli K-12 strain and its gcvB deletion derivative grown in minimal medium and identified putative targets responding to GcvB, including flu, a determinant gene of auto-aggregation. The following molecular studies and the enhanced auto-aggregation ability of the gcvB knockout strain further substantiated the induced expression of these genes. Intriguingly, the reduced expression of OxyR (the oxidative stress regulator) in the gcvB knockout strain was identified to account for the increased expression of flu. Additionally, GcvB was characterized to up-regulate the expression of OxyR at the translational level. Accordingly, compared to the wild type, the GcvB deletion strain was more sensitive to oxidative stress and lost some its ability to eliminate endogenous reactive oxygen species. Taken together, we reveal that GcvB regulates oxidative stress response by up-regulating OxyR expression. Our findings provide an insight into the diversity of GcvB regulation and add an additional layer to the regulation of OxyR.

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