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.

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 SodA Contributes to the Virulence of Avian PathogenicEscherichia coliO2 Strain E058 in Experimentally Infected Chickens

2019 ◽  
Vol 201 (6) ◽  
Author(s):  
Qingqing Gao ◽  
Le Xia ◽  
Xiaobo Wang ◽  
Zhengqin Ye ◽  
Jinbiao Liu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Virulence Factor ◽  
Infection Process ◽  
Strain Identification ◽  
Bacterial Disease ◽  
Wild Type ◽  
Content Type

ABSTRACTStrains of avian pathogenicEscherichia coli(APEC), the common pathogen of avian colibacillosis, encounter reactive oxygen species (ROS) during the infection process. Superoxide dismutases (SODs), acting as antioxidant factors, can protect against ROS-mediated host defenses. Our previous reports showed that thesodAgene (encoding a Mn-cofactor-containing SOD [MnSOD]) is highly expressed during the septicemic infection process of APEC.sodAhas been proven to be a virulence factor of certain pathogens, but its role in the pathogenicity of APEC has not been fully identified. In this study, we deleted thesodAgene from the virulent APEC O2 strain E058 and examined thein vitroandin vivophenotypes of the mutant. ThesodAmutant was more sensitive to hydrogen peroxide in terms of both its growth and viability than was the wild type. The ability to form a biofilm was weakened in thesodAmutant. ThesodAmutant was significantly more easily phagocytosed by chicken macrophages than was the wild-type strain. Chicken infection assays revealed significantly attenuated virulence of thesodAmutant compared with the wild type at 24 h postinfection. The virulence phenotype was restored by complementation of thesodAgene. Quantitative real-time reverse transcription-PCR revealed that the inactivation ofsodAreduced the expression of oxidative stress response geneskatE,perR, andosmCbut did not affect the expression ofsodBandsodC. Taken together, our studies indicate that SodA is important for oxidative resistance and virulence of APEC E058.IMPORTANCEAvian colibacillosis, caused by strains of avian pathogenicEscherichia coli, is a major bacterial disease of severe economic significance to the poultry industry worldwide. The virulence mechanisms of APEC are not completely understood. This study investigated the influence of an antioxidant protein, SodA, on the phenotype and pathogenicity of APEC O2 strain E058. This is the first report demonstrating that SodA plays an important role in protecting a specific APEC strain against hydrogen peroxide-induced oxidative stress and contributes to the virulence of this pathotype strain. Identification of this virulence factor will enhance our knowledge of APEC pathogenic mechanisms, which is crucial for designing successful strategies against associated infections and transmission.

scholarly journals Impact of Hydrogen Peroxide on Growth and Survival ofListeria MonocytogenesBiofilms

2010 ◽  
Vol 7 (3) ◽  
pp. 1008-1012
Author(s):  
Farhan Zameer ◽  
Shubha Gopal
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Listeria Monocytogenes ◽  
Stationary Phase ◽  
Adaptive Behavior ◽  
Potential Risk ◽  
Growth Cycle ◽  
Food Preservation ◽  
Survival Strategies ◽  
Growth And Survival

The present study aimed to understand the survival strategies adapted byListeria monocytogenesto combat oxidative stress in planktonic and biofilm cells with response to hydrogen peroxide (H2O2). The sensitivity ofL. monocytogenesto H2O2(oxidative stress) was found to vary in growth cycle. Early log phase cells were found to be sensitive to 100 μM H2O2when compared to stationary phase. Biofilm population was found to be resistant to the oxidative stress induced at 4% of H2O2when compared to their planktonic counterpart at 3.5%. This adaptive behavior allows the pathogen to overcome food preservation and safety barriers, which pose a potential risk to human health. The overall results suggest that, H2O2at a concentration of 6% could be used as a potent sanitizer for the elimination of listerial biofilms.

scholarly journals dprandsodin Streptococcus mutans Are Involved in Coexistence with S. sanguinis, and PerR Is Associated with Resistance to H2O2

2012 ◽  
Vol 79 (5) ◽  
pp. 1436-1443 ◽  
Author(s):  
Kei Fujishima ◽  
Miki Kawada-Matsuo ◽  
Yuichi Oogai ◽  
Masayuki Tokuda ◽  
Mitsuo Torii ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Mutans ◽  
Dental Plaque ◽  
Stress Factors ◽  
Wild Type ◽  
Content Type ◽  
Stress Genes ◽  
Large Numbers ◽  
Cariogenic Bacterium ◽  
Population Ratio

ABSTRACTLarge numbers of bacteria coexist in the oral cavity.Streptococcus sanguinis, one of the major bacteria in dental plaque, produces hydrogen peroxide (H2O2), which interferes with the growth of other bacteria.Streptococcus mutans, a cariogenic bacterium, can coexist withS. sanguinisin dental plaque, but to do so, it needs a means of detoxifying the H2O2produced byS. sanguinis. In this study, we investigated the association of three oxidative stress factors, Dpr, superoxide dismutase (SOD), and AhpCF, with the resistance ofS. sanguinisto H2O2. The knockout ofdprandsodsignificantly increased susceptibility to H2O2, while the knockout ofahpCFhad no apparent effect on susceptibility. In particular,dprinactivation resulted in hypersensitivity to H2O2. Next, we sought to identify the factor(s) involved in the regulation of these oxidative stress genes and found that PerR negatively regulateddprexpression. The knockout ofperRcaused increaseddprexpression levels, resulting in low-level susceptibility to H2O2compared with the wild type. Furthermore, we evaluated the roles ofperR,dpr, andsodwhenS. mutanswas cocultured withS. sanguinis. Culturing of thedprorsodmutant withS. sanguinisshowed a significant decrease in theS. mutanspopulation ratio compared with the wild type, while theperRmutant increased the ratio. Our results suggest thatdprandsodinS. mutansare involved in coexistence withS. sanguinis, and PerR is associated with resistance to H2O2in regulating the expression of Dpr.

scholarly journals Role of ςB in Heat, Ethanol, Acid, and Oxidative Stress Resistance and during Carbon Starvation inListeria monocytogenes

2001 ◽  
Vol 67 (10) ◽  
pp. 4454-4457 ◽  
Author(s):  
Adriana Ferreira ◽  
Conor P. O'Byrne ◽  
Kathryn J. Boor
Keyword(s):  
Oxidative Stress ◽  
Stationary Phase ◽  
Stress Resistance ◽  
Parent Strain ◽  
Acid Resistance ◽  
Carbon Starvation ◽  
Wild Type ◽  
Oxidative Stress Resistance ◽  
And Oxidative Stress ◽  
Dependent Mechanism

ABSTRACT To determine the contribution of sigma B (ςB) to survival of stationary-phase Listeria monocytogenescells following exposure to environmental stresses, we compared the viability of strain 10403S with that of an isogenic nonpolarsigB null mutant strain after exposure to heat (50°C), ethanol (16.5%), or acid (pH 2.5). Strain viabilities were also determined under the same conditions in cultures that had been previously exposed to sublethal levels of the same stresses (45°C, 5% ethanol, or pH 4.5). The ΔsigB and wild-type strains had similar viabilities following exposure to ethanol and heat, but the ΔsigB strain was almost 10,000-fold more susceptible to lethal acid stress than its parent strain. However, a 1-h preexposure to pH 4.5 yielded a 1,000-fold improvement in viability for the ΔsigB strain. These results suggest the existence in L. monocytogenes of both a ςB-dependent mechanism and a pH-dependent mechanism for acid resistance in the stationary phase. ςB contributed to resistance to both oxidative stress and carbon starvation inL. monocytogenes. The ΔsigB strain was 100-fold more sensitive to 13.8 mM cumene hydroperoxide than the wild-type strain. Following glucose depletion, the ΔsigB strain lost viability more rapidly than the parent strain. ςB contributions to viability during carbon starvation and to acid resistance and oxidative stress resistance support the hypothesis that ςB plays a role in protecting L. monocytogenes against environmental adversities.

scholarly journals Farnesol Induces Hydrogen Peroxide Resistance in Candida albicans Yeast by Inhibiting the Ras-Cyclic AMP Signaling Pathway

2010 ◽  
Vol 9 (4) ◽  
pp. 569-577 ◽  
Author(s):  
Aurélie Deveau ◽  
Amy E. Piispanen ◽  
Angelyca A. Jackson ◽  
Deborah A. Hogan
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Candida Albicans ◽  
Adenylate Cyclase ◽  
Signaling Pathway ◽  
Stress Resistance ◽  
Ros Generation ◽  
Signaling Molecule ◽  
Content Type ◽  
Oxidative Stress Resistance

ABSTRACT Farnesol, a Candida albicans cell-cell signaling molecule that participates in the control of morphology, has an additional role in protection of the fungus against oxidative stress. In this report, we show that although farnesol induces the accumulation of intracellular reactive oxygen species (ROS), ROS generation is not necessary for the induction of catalase (Cat1)-mediated oxidative-stress resistance. Two antioxidants, α-tocopherol and, to a lesser extent, ascorbic acid effectively reduced intracellular ROS generation by farnesol but did not alter farnesol-induced oxidative-stress resistance. Farnesol inhibits the Ras1-adenylate cyclase (Cyr1) signaling pathway to achieve its effects on morphology under hypha-inducing conditions, and we demonstrate that farnesol induces oxidative-stress resistance by a similar mechanism. Strains lacking either Ras1 or Cyr1 no longer exhibited increased protection against hydrogen peroxide upon preincubation with farnesol. While we also observed the previously reported increase in the phosphorylation level of Hog1, a known regulator of oxidative-stress resistance, in the presence of farnesol, the hog1/hog1 mutant did not differ from wild-type strains in terms of farnesol-induced oxidative-stress resistance. Analysis of Hog1 levels and its phosphorylation states in different mutant backgrounds indicated that mutation of the components of the Ras1-adenylate cyclase pathway was sufficient to cause an increase of Hog1 phosphorylation even in the absence of farnesol or other exogenous sources of oxidative stress. This finding indicates the presence of unknown links between these signaling pathways. Our results suggest that farnesol effects on the Ras-adenylate cyclase cascade are responsible for many of the observed activities of this fungal signaling molecule.

scholarly journals Bactericidal Antibiotics Do Not Appear To Cause Oxidative Stress in Listeria monocytogenes

2012 ◽  
Vol 78 (12) ◽  
pp. 4353-4357 ◽  
Author(s):  
Louise Feld ◽  
Gitte M. Knudsen ◽  
Lone Gram
Keyword(s):  
Oxidative Stress ◽  
Listeria Monocytogenes ◽  
Lethal Effect ◽  
Common Mechanism ◽  
Human Pathogen ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
And Oxidative Stress ◽  
Internal Production

ABSTRACTOxidative stress can be an important contributor to the lethal effect of bactericidal antibiotics in some bacteria, such asEscherichia coliandStaphylococcus aureus. Thus, despite the different target-specific actions of bactericidal antibiotics, they have a common mechanism leading to bacterial self-destruction by internal production of hydroxyl radicals. The purpose of the present study was to determine if a similar mechanism is involved in antibiotic killing of the infectious human pathogen,Listeria monocytogenes. We treated wild-typeL. monocytogenesand oxidative stress mutants (Δsodand Δfri) with three different bactericidal antibiotics and found no difference in killing kinetics. In contrast, wild-typeE. coliand an oxidative stress mutant (ΔsodAΔsodB) differed significantly in their sensitivity to bactericidal antibiotics. We conclude that bactericidal antibiotics did not appear to cause oxidative stress inL. monocytogenesand propose that this is caused by its noncyclic tricarboxylic acid (TCA) pathway. Hence, in this noncyclic metabolism, there is a decoupling between the antibiotic-mediated cellular requirement for NADH and the induction of TCA enzyme activity, which is believed to mediate the oxidative stress reaction.

scholarly journals Roles of Four Putative DEAD-Box RNA Helicase Genes in Growth of Listeria monocytogenes EGD-e under Heat, pH, Osmotic, Ethanol, and Oxidative Stress Conditions

2012 ◽  
Vol 78 (19) ◽  
pp. 6875-6882 ◽  
Author(s):  
Annukka Markkula ◽  
Miia Lindström ◽  
Per Johansson ◽  
Johanna Björkroth ◽  
Hannu Korkeala
Keyword(s):  
Oxidative Stress ◽  
Listeria Monocytogenes ◽  
Stress Tolerance ◽  
Deletion Mutant ◽  
Rna Helicase ◽  
Wild Type ◽  
Content Type ◽  
Oxidative Stresses ◽  
Dead Box ◽  
Mutant Strains

ABSTRACTTo examine the role of the four putative DEAD-box RNA helicase genes ofListeria monocytogenesEGD-e in stress tolerance, the growth of the Δlmo0866, Δlmo1246, Δlmo1450, and Δlmo1722deletion mutant strains at 42.5°C, at pH 5.6 or pH 9.4, in 6% NaCl, in 3.5% ethanol, and in 5 mM H2O2was studied. Restricted growth of the Δlmo0866deletion mutant strain in 3.5% ethanol suggests that Lmo0866 contributes to ethanol stress tolerance ofL. monocytogenesEGD-e. The Δlmo1450mutant strain showed negligible growth at 42.5°C, at pH 9.4, and in 5 mM H2O2and a lower maximum growth temperature than the wild-type EGD-e, suggesting that Lmo1450 is involved in the tolerance ofL. monocytogenesEGD-e to heat, alkali, and oxidative stresses. The altered stress tolerance of the Δlmo0866and Δlmo1450deletion mutant strains did not correlate with changes in relative expression levels oflmo0866andlmo1450genes under corresponding stresses, suggesting that Lmo0866- and Lmo1450-dependent tolerance to heat, alkali, ethanol, or oxidative stress is not regulated at the transcriptional level. Growth of the Δlmo1246and Δlmo1722deletion mutant strains did not differ from that of the wild-type EGD-e under any of the conditions tested, suggesting that Lmo1246 and Lmo1722 have no roles in the growth ofL. monocytogenesEGD-e under heat, pH, osmotic, ethanol, or oxidative stress. This study shows that the putative DEAD-box RNA helicase geneslmo0866andlmo1450play important roles in tolerance ofL. monocytogenesEGD-e to ethanol, heat, alkali, and oxidative stresses.

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 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.

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