scholarly journals Lack of DNA helicase Pif1 disrupts zinc and iron homoeostasis in yeast

2010 ◽  
Vol 432 (3) ◽  
pp. 595-608 ◽  
Author(s):  
María Guirola ◽  
Lina Barreto ◽  
Ayelen Pagani ◽  
Miriam Romagosa ◽  
Antonio Casamayor ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Responses ◽  
Nuclear Dna ◽  
Transcriptional Profiling ◽  
Growth Conditions ◽  
Protective Role ◽  
Dna Helicase ◽  
Dna Integrity ◽  
Zinc Tolerance ◽  
Genes Encoding

The Saccharomyces cerevisiae gene PIF1 encodes a conserved eukaryotic DNA helicase required for both mitochondrial and nuclear DNA integrity. Our previous work revealed that a pif1Δ strain is tolerant to zinc overload. In the present study we demonstrate that this effect is independent of the Pif1 helicase activity and is only observed when the protein is absent from the mitochondria. pif1Δ cells accumulate abnormal amounts of mitochondrial zinc and iron. Transcriptional profiling reveals that pif1Δ cells under standard growth conditions overexpress aconitase-related genes. When exposed to zinc, pif1Δ cells show lower induction of genes encoding iron (siderophores) transporters and higher expression of genes related to oxidative stress responses than wild-type cells. Coincidently, pif1Δ mutants are less prone to zinc-induced oxidative stress and display a higher reduced/oxidized glutathione ratio. Strikingly, although pif1Δ cells contain normal amounts of the Aco1 (yeast aconitase) protein, they completely lack aconitase activity. Loss of Aco1 activity is also observed when the cell expresses a non-mitochondrially targeted form of Pif1. We postulate that lack of Pif1 forces aconitase to play its DNA protective role as a nucleoid protein and that this triggers a domino effect on iron homoeostasis resulting in increased zinc tolerance.

scholarly journals Copper Stress Induces a Global Stress Response in Staphylococcus aureus and Represses sae and agr Expression and Biofilm Formation

2009 ◽  
Vol 76 (1) ◽  
pp. 150-160 ◽  
Author(s):  
Jonathan Baker ◽  
Sutthirat Sitthisak ◽  
Mrittika Sengupta ◽  
Miranda Johnson ◽  
R. K. Jayaswal ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Transcriptional Profiling ◽  
Resistance Mechanism ◽  
Growth Conditions ◽  
Copper Resistance ◽  
Transcriptional Analysis ◽  
Copper Stress ◽  
High Copper

ABSTRACT Copper is an important cofactor for many enzymes; however, high levels of copper are toxic. Therefore, bacteria must ensure there is sufficient copper for use as a cofactor but, more importantly, must limit free intracellular levels to prevent toxicity. In this study, we have used DNA microarray to identify Staphylococcus aureus copper-responsive genes. Transcriptional profiling of S. aureus SH1000 grown in excess copper identified a number of genes which fall into four groups, suggesting that S. aureus has four main mechanisms for adapting to high levels of environmental copper, as follows: (i) induction of direct copper homeostasis mechanisms; (ii) increased oxidative stress resistance; (iii) expression of the misfolded protein response; and (iv) repression of a number of transporters and global regulators such as Agr and Sae. Our experimental data confirm that resistance to oxidative stress and particularly to H2O2 scavenging is an important S. aureus copper resistance mechanism. Our previous studies have demonstrated that Eap and Emp proteins, which are positively regulated by Agr and Sae, are required for biofilm formation under low-iron growth conditions. Our transcriptional analysis has confirmed that sae, agr, and eap are repressed under high-copper conditions and that biofilm formation is indeed repressed under high-copper conditions. Therefore, our results may provide an explanation for how copper films can prevent biofilm formation on catheters.

scholarly journals Cytochrome bd Oxidase, Oxidative Stress, and Dioxygen Tolerance of the Strictly Anaerobic Bacterium Moorella thermoacetica

2005 ◽  
Vol 187 (6) ◽  
pp. 2020-2029 ◽  
Author(s):  
Amaresh Das ◽  
Radu Silaghi-Dumitrescu ◽  
Lars G. Ljungdahl ◽  
Donald M. Kurtz
Keyword(s):  
Oxidative Stress ◽  
Growth Conditions ◽  
Strictly Anaerobic ◽  
Paramagnetic Resonance ◽  
Cysteine Synthase ◽  
Moorella Thermoacetica ◽  
Genes Encoding ◽  
Uptake Activity ◽  
Acetogenic Bacterium ◽  
Cytochrome Bd Oxidase

ABSTRACT The gram-positive, thermophilic, acetogenic bacterium Moorella thermoacetica can reduce CO2 to acetate via the Wood-Ljungdahl (acetyl coenzyme A synthesis) pathway. This report demonstrates that, despite its classification as a strict anaerobe, M. thermoacetica contains a membrane-bound cytochrome bd oxidase that can catalyze reduction of low levels of dioxygen. Whole-cell suspensions of M. thermoacetica had significant endogenous O2 uptake activity, and this activity was increased in the presence of methanol or CO, which are substrates in the Wood-Ljungdahl pathway. Cyanide and azide strongly (∼70%) inhibited both the endogenous and CO/methanol-dependent O2 uptake. UV-visible light absorption and electron paramagnetic resonance spectra of n-dodecyl-β-maltoside extracts of M. thermoacetica membranes showed the presence of a cytochrome bd oxidase complex containing cytochrome b 561, cytochrome b 595, and cytochrome d (chlorin). Subunits I and II of the bd oxidase were identified by N-terminal amino acid sequencing. The M. thermoacetica cytochrome bd oxidase exhibited cyanide-sensitive quinol oxidase activity. The M. thermoacetica cytochrome bd (cyd) operon consists of four genes, encoding subunits I and II along with two ABC-type transporter proteins, homologs of which in other bacteria are required for assembly of the bd complex. The level of this cyd operon transcript was significantly increased when M. thermoacetica was grown in the absence of added reducing agent (cysteine + H2S). Expression of a 35-kDa cytosolic protein, identified as a cysteine synthase (CysK), was also induced by the nonreducing growth conditions. The combined evidence indicates that cytochrome bd oxidase and cysteine synthase protect against oxidative stress and contribute to the limited dioxygen tolerance of M. thermoacetica.

scholarly journals IPSE, a urogenital parasite-derived immunomodulatory protein, ameliorates ifosfamide-induced hemorrhagic cystitis through downregulation of pro-inflammatory pathways

2018 ◽  
Author(s):  
Evaristus C. Mbanefo ◽  
Loc Le ◽  
Rebecca Zee ◽  
Nirad Banskota ◽  
Kenji Ishida ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Responses ◽  
Cellular Proliferation ◽  
Transcriptional Profiling ◽  
Hemorrhagic Cystitis ◽  
Underlying Mechanism ◽  
Protective Mechanism ◽  
Therapeutic Effects ◽  
Anti Inflammatory ◽  
Oxidative Stress Responses

AbstractIfosfamide and other oxazaphosphorines can result in hemorrhagic cystitis, a constellation of complications caused by acrolein metabolites. We previously showed that a single dose of IPSE, a schistosome-derived host modulatory protein, can ameliorate ifosfamide-related cystitis; however, the exact mechanisms underlying this urotoxic effect and its prevention are not fully understood. To provide insights into IPSE’s protective mechanism, we undertook transcriptional profiling of bladders from ifosfamide-treated mice, with or without IPSE pretreatment. Following ifosfamide challenge, there was upregulation of a range of pro-inflammatory genes. The pro-inflammatory pathway involving the IL-1β, TNFαand IL-6 triad via NFκB and STAT3 signaling pathways was identified as the key driver of inflammation. The NRF2-mediated oxidative stress response pathway, which regulates bothHmox1-mediated heme homoeostasis and expression of antioxidant enzymes, was highly activated. Anti-inflammatory and cellular proliferation cascades implicated in tissue repair, namely Wnt, Hedgehog and PPAR pathways, were downregulated. IPSE administration before ifosfamide injection resulted in significant downregulation of major proinflammatory pathways including the triad of IL-1β, TNFαand IL-6 pathways, the interferon signaling pathway, and less apparent reduction in oxidative stress responses. Taken together, we have identified signatures of acute phase inflammation and oxidative stress responses in the ifosfamide-injured bladder, which are reversed by pretreatment with IPSE, a parasite derived anti-inflammatory molecule. In addition to providing new insights into the underlying mechanism of IPSE’s therapeutic effects, this work has revealed several pathways that could be therapeutically targeted to prevent and treat ifosfamide-induced hemorrhagic cystitis.

scholarly journals Transcriptional and Physiological Responses of Bradyrhizobium japonicum to Desiccation-Induced Stress

2007 ◽  
Vol 189 (19) ◽  
pp. 6751-6762 ◽  
Author(s):  
Eddie J. Cytryn ◽  
Dipen P. Sangurdekar ◽  
John G. Streeter ◽  
William L. Franck ◽  
Woo-suk Chang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Responses ◽  
Bradyrhizobium Japonicum ◽  
Isocitrate Lyase ◽  
Open Reading Frames ◽  
Membrane Repair ◽  
Trehalose Synthase ◽  
Damage Stability ◽  
Genes Encoding ◽  
Oxidative Stress Responses

ABSTRACT The growth and persistence of rhizobia and bradyrhizobia in soils are negatively impacted by drought conditions. In this study, we used genome-wide transcriptional analyses to obtain a comprehensive understanding of the response of Bradyrhizobium japonicum to drought. Desiccation of cells resulted in the differential expression of 15 to 20% of the 8,480 B. japonicum open reading frames, with considerable differentiation between early (after 4 h) and late (after 24 and 72 h) expressed genes. While 225 genes were universally up-regulated at all three incubation times in response to desiccation, an additional 43 and 403 up-regulated genes were common to the 4/24- and 24/72-h incubation times, respectively. Desiccating conditions resulted in the significant induction (>2.0-fold) of the trehalose-6-phosphate synthetase (otsA), trehalose-6-phosphate phosphatase (otsB), and trehalose synthase (treS) genes, which encode two of the three trehalose synthesis pathways found in B. japonicum. Gene induction was correlated with an elevated intracellular concentration of trehalose and increased activity of trehalose-6-phosphate synthetase, collectively supporting the hypothesis that this disaccharide plays a prominent and important role in promoting desiccation tolerance in B. japonicum. Microarray data also indicated that σ54- and σ24-associated transcriptional regulators and genes encoding isocitrate lyase, oxidative stress responses, the synthesis and transport of exopolysaccharides, heat shock response proteins, enzymes for the modification and repair of nucleic acids, and the synthesis of pili and flagella are also involved in the response of B. japonicum to desiccation. Polyethylene glycol-generated osmotic stress induced significantly fewer genes than those transcriptionally activated by desiccation. However, 67 genes were commonly induced under both conditions. Taken together, these results suggest that B. japonicum directly responds to desiccation by adapting to changes imparted by reduced water activity, such as the synthesis of trehalose and polysaccharides and, secondarily, by the induction of a wide variety of proteins involved in protection of the cell membrane, repair of DNA damage, stability and integrity of proteins, and oxidative stress responses.

scholarly journals Large-Scale Gene Discovery in the Oomycete Phytophthora infestans Reveals Likely Components of Phytopathogenicity Shared with True Fungi

2005 ◽  
Vol 18 (3) ◽  
pp. 229-243 ◽  
Author(s):  
Thomas A. Randall ◽  
Rex A. Dwyer ◽  
Edgar Huitema ◽  
Katinka Beyer ◽  
Cristina Cvitanich ◽  
...  
Keyword(s):  
Phytophthora Infestans ◽  
Stress Responses ◽  
Large Scale ◽  
Developmental Stages ◽  
Sequence Data ◽  
Growth Conditions ◽  
Gene Content ◽  
Cdna Libraries ◽  
Class Iii ◽  
Genes Encoding

To overview the gene content of the important pathogen Phytophthora infestans, large-scale cDNA and genomic sequencing was performed. A set of 75,757 high-quality expressed sequence tags (ESTs) from P. infestans was obtained from 20 cDNA libraries representing a broad range of growth conditions, stress responses, and developmental stages. These included libraries from P. infestans-potato and -tomato interactions, from which 963 pathogen ESTs were identified. To complement the ESTs, onefold coveragethe P. infestans genome was obtained and regions of coding potential identified. A unigene set of 18,256 sequences was derived from the EST and genomic data and characterized for potential functions, stage-specific patterns of expression, and codon bias. Cluster analysis of ESTs revealed major differences between the expressed gene content of mycelial and spore-related stages, and affinities between some growth conditions. Comparisons with databases of fungal pathogenicity genes revealed conserved elements of pathogenicity, such as class III pectate lyases, despite the considerable evolutionary distance between oomycetes and fungi. Thirty-seven genes encoding components of flagella also were identified. Several genes not anticipated to occur in oomycetes were detected, including chitin synthases, phosphagen kinases, and a bacterial-type FtsZ cell-division protein. The sequence data described are available in a searchable public database.

scholarly journals Transcriptional profiling of Mycoplasma hyopneumoniae during iron depletion using microarrays

Microbiology ◽  
2006 ◽  
Vol 152 (4) ◽  
pp. 937-944 ◽  
Author(s):  
Melissa L. Madsen ◽  
Dan Nettleton ◽  
Eileen L. Thacker ◽  
F. Chris Minion
Keyword(s):  
Respiratory Disease ◽  
Transcriptional Profiling ◽  
Mycoplasma Hyopneumoniae ◽  
Growth Conditions ◽  
Iron Deprivation ◽  
Genes Encoding ◽  
Control Programmes ◽  
Host Innate Immune Response ◽  
Porcine Respiratory

Mycoplasma hyopneumoniae, the causative agent of swine enzootic pneumonia and a major component of the porcine respiratory disease complex, continues to confound swine producers despite control programmes worldwide. The disease is chronic and self-limiting, but the host is subject to immunopathological changes that potentiate respiratory disease associated with other pathogens. The response of M. hyopneumoniae to environmental stress is of interest because of its relevance to virulence mechanisms in other bacterial pathogens. One of these stressors, iron deprivation, is a prominent feature of the host innate immune response, and most certainly impacts growth of mycoplasmas in vivo. To study this, microarray technology was applied to the transcriptome analysis of M. hyopneumoniae during iron deprivation. An array consisting of 632 of the 698 ORFs in the genome was used to compare the mRNA isolated from organisms grown under normal laboratory conditions with that from organisms subjected to iron deprivation with the chelator 2,2′-dipyridyl. This analysis identified 27 genes that were either up- or down-regulated in response to low-iron growth conditions (P<0·01), with an estimated false discovery rate below 10 %. These included genes encoding transport proteins, enzymes involved in energy metabolism, and components of the translation process. Ten of the 27 identified genes had no assigned function. These studies indicate that M. hyopneumoniae can respond to changes in environmental conditions, but the mechanism employed remains unknown.

scholarly journals Senataxin: A New Guardian of the Female Germline Important for Delaying Ovarian Aging

2021 ◽  
Vol 12 ◽  
Author(s):  
Hayden A. Homer
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Ovarian Reserve ◽  
Ovarian Function ◽  
Dna Helicase ◽  
Dna Integrity ◽  
Low Grade ◽  
Critical Determinant ◽  
Oocyte Growth ◽  
Ovarian Aging

Early decline in ovarian function known as premature ovarian aging (POA) occurs in around 10% of women and is characterized by a markedly reduced ovarian reserve. Premature ovarian insufficiency (POI) affects ~1% of women and refers to the severe end of the POA spectrum in which, accelerated ovarian aging leads to menopause before 40 years of age. Ovarian reserve refers to the total number of follicle-enclosed oocytes within both ovaries. Oocyte DNA integrity is a critical determinant of ovarian reserve since damage to DNA of oocytes within primordial-stage follicles triggers follicular apoptosis leading to accelerated follicle depletion. Despite the high prevalence of POA, very little is known regarding its genetic causation. Another little-investigated aspect of oocyte DNA damage involves low-grade damage that escapes apoptosis at the primordial follicle stage and persists throughout oocyte growth and later follicle development. Senataxin (SETX) is an RNA/DNA helicase involved in repair of oxidative stress-induced DNA damage and is well-known for its roles in preventing neurodegenerative disease. Recent findings uncover an important role for SETX in protecting oocyte DNA integrity against aging-induced increases in oxidative stress. Significantly, this newly identified SETX-mediated regulation of oocyte DNA integrity is critical for preventing POA and early-onset female infertility by preventing premature depletion of the ovarian follicular pool and reducing the burden of low-grade DNA damage both in primordial and fully-grown oocytes.

scholarly journals The zinc cluster transcription factor Rha1 is a positive filamentation regulator in Candida albicans

2020 ◽  
Author(s):  
Raha Parvizi Omran ◽  
Chris Law ◽  
Vanessa Dumeaux ◽  
Joachim Morschhäuser ◽  
Malcolm Whiteway
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Transcription Factors ◽  
Transcriptional Profiling ◽  
Hyphal Growth ◽  
Growth Conditions ◽  
Hyphal Development ◽  
Zinc Cluster ◽  
Genes Encoding

AbstractZinc cluster transcription factors are essential fungal specific regulators of gene expression. In the dimorphic pathogen Candida albicans, they control processes ranging from metabolism and stress adaptation to mating, virulence, and antifungal resistance. Here, we have identified the gene CaORF19.1604 as encoding a zinc cluster transcription factor that acts as a regulator of filament development. Hyperactivation of CaORF19.1604, which we have named RHA1 for Regulator of Hyphal Activity, leads to a wrinkled colony morphology under non-hyphal growth conditions, to pseudohyphal growth and filament formation, to invasiveness and enhanced biofilm formation.  Cells with activated Rha1 are sensitive to cell wall modifying agents such as Congo red and the echinocandin drug caspofungin but show normal sensitivity to fluconazole. RNA-sequencing-based transcriptional profiling of the activated Rha1 strain reveals the up-regulation of genes for core filamentation and cell-wall-adhesion-related proteins such as Als1, Als3, Ece1, and Hwp1. Upregulation is also seen for the genes for the hyphal-inducing transcription factors Brg1 and Ume6 and genes encoding several enzymes involved in arginine metabolism, while downregulation is seen for the hyphal repressor Nrg1. The deletion of BRG1 blocks the filamentation caused by activated Rha1, while null mutants of UME6 result in a partial block. Deletion of RHA1 can partially reduce healthy hyphal development triggered by environmental conditions such as Spider medium or serum at 37°C.In contrast to the limited effect of either single mutant, the double rha1 ume6 deletion strain is totally defective in both serum and Spider medium stimulated hyphal development. While the loss of Brg1 function blocks serum-stimulated hyphal development, this block can be significantly bypassed by Rha1 hyperactivity, and the combination of Rha1 hyperactivity and serum addition can generate significant polarization in even brg1 ume6 double mutants. Our results thus suggest that in response to external signals, Rha1 functions to facilitate the switch from an Nrg1 controlled yeast state to a Brg1/Ume6 regulated hyphal state.Author SummaryCandida albicans is the predominant human fungal pathogen, generating a mortality rate of 40% in systemically infected patients. The ability of Candida albicans to change its morphology is a determinant of its tissue penetration and invasion in response to variant host-related stimuli. The regulatory mechanism for filamentation includes a complex network of transcription factors that play roles in regulating hyphae associated genes. We identify here a new regulator of filamentation from the zinc cluster transcription factor family. We present evidence suggesting that this transcription factor assists the Nrg1/Brg1 switch regulating hyphal development.

scholarly journals Transcriptional Profiling of Neisseria meningitidis Interacting with Human Epithelial Cells in a Long-TermIn VitroColonization Model

2013 ◽  
Vol 81 (11) ◽  
pp. 4149-4159 ◽  
Author(s):  
Ariann Hey ◽  
Ming-Shi Li ◽  
Michael J. Hudson ◽  
Paul R. Langford ◽  
J. Simon Kroll
Keyword(s):  
Epithelial Cell ◽  
Neisseria Meningitidis ◽  
Transcriptional Profiling ◽  
Growth Conditions ◽  
Epithelial Cell Line ◽  
Content Type ◽  
Genes Encoding ◽  
Interesting Candidate ◽  
Life Threatening

ABSTRACTNeisseria meningitidisis a commensal of humans that can colonize the nasopharyngeal epithelium for weeks to months and occasionally invades to cause life-threatening septicemia and meningitis. Comparatively little is known about meningococcal gene expression during colonization beyond those first few hours. In this study, the transcriptome of adherent serogroup BN. meningitidisstrain MC58 was determined at intervals during prolonged cocultivation with confluent monolayers of the human respiratory epithelial cell line 16HBE14. At different time points up to 21 days, 7 to 14% of the meningococcal genome was found to be differentially regulated. The transcriptome of adherent meningococci obtained after 4 h of coculture was markedly different from that obtained after prolonged cocultivation (24 h, 96 h, and 21 days). Genes persistently upregulated during prolonged cocultivation included three genes (hfq,misR/phoP, andlrp) encoding global regulatory proteins. Many genes encoding known adhesins involved in epithelial adherence were upregulated, including those of a novel locus (spanningNMB0342toNMB0348[NMB0342-NMB0348]) encoding epithelial cell-adhesive function. Sixteen genes (includingporA,porB,rmpM, andfbpA) encoding proteins previously identified by their immunoreactivity to sera from individuals colonized long term with serogroup B meningococci were also upregulated during prolonged cocultivation, indicating that our system models growth conditionsin vivoduring the commensal state. Surface-expressed proteins downregulated in the nasopharynx (and thus less subject to selection pressure) but upregulated in the bloodstream (and thus vulnerable to antibody-mediated bactericidal activity) should be interesting candidate vaccine antigens, and in this study, three new proteins fulfilling these criteria have been identified: NMB0497, NMB0866, and NMB1882.

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