An AraC/XylS Family Transcriptional Regulator Modulates the Oxidative Stress Response of Francisella tularensis

Francisella tularensis is a Gram-negative bacterium that causes a fatal human disease known as tularemia. The Centers for Disease Control have classified F. tularensis as Category A Tier-1 Select Agent. The virulence mechanisms of Francisella are not entirely understood. Francisella possesses very few transcription regulators, and most of these regulate the expression of genes involved in intracellular survival and virulence. The F. tularensis genome sequence analysis reveals an AraC ( FTL_ 0689) transcriptional regulator homologous to the AraC/XylS family of transcriptional regulators. In Gram-negative bacteria, AraC activates genes required for L-arabinose utilization and catabolism. The role of the FTL_ 0689 regulator in F. tularensis is not known. In this study, we characterized the role of FTL_ 0689 in gene regulation of F. tularensis and investigated its contribution to intracellular survival and virulence. The results demonstrate that FTL_0689 in Francisella is not required for L-arabinose utilization. Instead, FTL_ 0689 specifically regulates the expression of the oxidative and global stress response, virulence, metabolism, and other key pathways genes required by Francisella when exposed to oxidative stress. The FTL_0689 mutant is attenuated for intramacrophage growth and virulence in mice. Based on the deletion mutant phenotype, FTL_0689 was termed osrR ( o xidative s tress r esponse r egulator). Altogether, this study elucidates the role of the osrR transcriptional regulator in tularemia pathogenesis. IMPORTANCE: The virulence mechanisms of category A select agent Francisella tularensis , the causative agent of a fatal human disease known as tularemia, remain largely undefined. The present study investigated the role of a transcriptional regulator and its overall contribution to the oxidative stress resistance of F. tularensis . The results provide an insight into a novel gene regulatory mechanism, especially when Francisella is exposed to oxidative stress conditions. Understanding such Francisella - specific regulatory mechanisms will identify potential targets for developing effective therapies and vaccines to prevent tularemia.

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Stringent Response Governs the Virulence and Oxidative Stress Resistance of Francisella tularensis

10.1101/653790 ◽

2019 ◽

Author(s):

Zhuo Ma ◽

Kayla King ◽

Maha Alqahtani ◽

Madeline Worden ◽

Parthasarthy Muthuraman ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Francisella Tularensis ◽

Stress Resistance ◽

Stringent Response ◽

Oxidative Stress Response ◽

Stress Conditions ◽

Gram Negative ◽

And Oxidative Stress ◽

Starvation Conditions

AbstractFrancisella tularensis is a Gram-negative bacterium responsible for causing tularemia in the northern hemisphere. F. tularensis has long been developed as a biological weapon due to its ability to cause severe illness upon inhalation of as few as ten organisms and based on its potential to be used as a bioterror agent is now classified as a Tier 1 Category A select agent by the CDC. The stringent response facilitates bacterial survival under nutritionally challenging starvation conditions. The hallmark of stringent response is the accumulation of the effector molecules ppGpp and (p)ppGpp known as stress alarmones. The relA and spoT gene products generate alarmones in several Gram-negative bacterial pathogens. RelA is a ribosome-associated ppGpp synthetase that gets activated under amino acid starvation conditions whereas, SpoT is a bifunctional enzyme with both ppGpp synthetase and ppGpp hydrolase activities. Francisella encodes a monofunctional RelA and a bifunctional SpoT enzyme. Previous studies have demonstrated that stringent response under nutritional stresses increases expression of virulence-associated genes encoded on Francisella Pathogenicity Island. This study investigated how stringent response governs the oxidative stress response of F. tularensis. We demonstrate that RelA/SpoT-mediated ppGpp production alters global gene transcriptional profile of F. tularensis in the presence of oxidative stress. The lack of stringent response in relA/spoT gene deletion mutants of F. tularensis makes bacteria more susceptible to oxidants, attenuates survival in macrophages, and virulence in mice. Mechanistically, we provide evidence that the stringent response in Francisella contributes to oxidative stress resistance by enhancing the production of antioxidant enzymes.ImportanceThe unique intracellular life cycle of Francisella in addition to nutritional stress also exposes the bacteria to oxidative stress conditions upon its brief residence in the phagosomes, and escape into the cytosol where replication takes place. However, the contribution of the stringent response in gene regulation and management of the oxidative stress response when Francisella is experiencing oxidative stress conditions is not known. Our results provide a link between the stringent and oxidative stress responses. This study further improves our understanding of the intracellular survival mechanisms of F. tularensis.

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

PLoS ONE ◽

10.1371/journal.pone.0124582 ◽

2015 ◽

Vol 10 (4) ◽

pp. e0124582 ◽

Cited By ~ 27

Author(s):

Ramona Jühlen ◽

Jan Idkowiak ◽

Angela E. Taylor ◽

Barbara Kind ◽

Wiebke Arlt ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Oxidative Stress Response ◽

Adrenocortical Cells

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Reassessing the Role of the Type II MqsRA Toxin-Antitoxin System in Stress Response and Biofilm Formation: mqsA Is Transcriptionally Uncoupled from mqsR

mBio ◽

10.1128/mbio.02678-19 ◽

2019 ◽

Vol 10 (6) ◽

Cited By ~ 11

Author(s):

Nathan Fraikin ◽

Clothilde J. Rousseau ◽

Nathalie Goeders ◽

Laurence Van Melderen

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Biofilm Formation ◽

Bile Salts ◽

Regulatory Networks ◽

Constitutive Expression ◽

Toxin Gene ◽

Global Regulator ◽

Bacterial Physiology

ABSTRACT Toxin-antitoxin (TA) systems are broadly distributed modules whose biological roles remain mostly unknown. The mqsRA system is a noncanonical TA system in which the toxin and antitoxins genes are organized in operon but with the particularity that the toxin gene precedes that of the antitoxin. This system was shown to regulate global processes such as resistance to bile salts, motility, and biofilm formation. In addition, the MqsA antitoxin was shown to be a master regulator that represses the transcription of the csgD, cspD, and rpoS global regulator genes, thereby displaying a pleiotropic regulatory role. Here, we identified two promoters located in the toxin sequence driving the constitutive expression of mqsA, allowing thereby excess production of the MqsA antitoxin compared to the MqsR toxin. Our results show that both antitoxin-specific and operon promoters are not regulated by stresses such as amino acid starvation, oxidative shock, or bile salts. Moreover, we show that the MqsA antitoxin is not a global regulator as suggested, since the expression of csgD, cspD and rpoS is similar in wild-type and ΔmqsRA mutant strains. Moreover, these two strains behave similarly in terms of biofilm formation and sensitivity to oxidative stress or bile salts. IMPORTANCE There is growing controversy regarding the role of chromosomal toxin-antitoxin systems in bacterial physiology. mqsRA is a peculiar toxin-antitoxin system, as the gene encoding the toxin precedes that of the antitoxin. This system was previously shown to play a role in stress response and biofilm formation. In this work, we identified two promoters specifically driving the constitutive expression of the antitoxin, thereby decoupling the expression of antitoxin from the toxin. We also showed that mqsRA contributes neither to the regulation of biofilm formation nor to the sensitivity to oxidative stress and bile salts. Finally, we were unable to confirm that the MqsA antitoxin is a global regulator. Altogether, our data are ruling out the involvement of the mqsRA system in Escherichia coli regulatory networks.

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

Mechanisms of Ageing and Development ◽

10.1016/j.mad.2013.03.006 ◽

2013 ◽

Vol 134 (5-6) ◽

pp. 261-269 ◽

Cited By ~ 21

Author(s):

Mariarosaria D’Errico ◽

Barbara Pascucci ◽

Egidio Iorio ◽

Bennett Van Houten ◽

Eugenia Dogliotti

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Oxidative Stress Response

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Catalase Expression inAzospirillum brasilenseSp7 Is Regulated by a Network Consisting of OxyR and Two RpoH Paralogs and Including an RpoE1→RpoH5 Regulatory Cascade

Applied and Environmental Microbiology ◽

10.1128/aem.01787-18 ◽

2018 ◽

Vol 84 (23) ◽

Cited By ~ 2

Author(s):

Ashutosh Kumar Rai ◽

Sudhir Singh ◽

Sushil Kumar Dwivedi ◽

Amit Srivastava ◽

Parul Pandey ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Sinorhizobium Meliloti ◽

Deinococcus Radiodurans ◽

Oxidative Stress Response ◽

Sigma Factors ◽

Transcriptional Analysis ◽

Content Type ◽

Regulatory Cascade ◽

Transcription Regulators

ABSTRACTThe genome ofAzospirillum brasilenseencodes five RpoH sigma factors: two OxyR transcription regulators and three catalases. The aim of this study was to understand the role they play during oxidative stress and their regulatory interconnection. Out of the 5 paralogs of RpoH present inA. brasilense, inactivation of onlyrpoH1rendersA. brasilenseheat sensitive. While transcript levels ofrpoH1were elevated by heat stress, those ofrpoH3andrpoH5were upregulated by H2O2. Catalase activity was upregulated inA. brasilenseand itsrpoH::kmmutants in response to H2O2except in the case of therpoH5::kmmutant, suggesting a role for RpoH5 in regulating inducible catalase. Transcriptional analysis of thekatN,katAI, andkatAII genes revealed that the expression ofkatNandkatAII was severely compromised in therpoH3::kmandrpoH5::kmmutants, respectively. Regulation ofkatNandkatAII by RpoH3 and RpoH5, respectively, was further confirmed in anEscherichia colitwo-plasmid system. Regulation ofkatAII by OxyR2 was evident by a drastic reduction in growth, KatAII activity, andkatAII::lacZexpression in anoxyR2::kmmutant. This study reports the involvement of RpoH3 and RpoH5 sigma factors in regulating oxidative stress response in alphaproteobacteria. We also report the regulation of an inducible catalase by a cascade of alternative sigma factors and an OxyR. Out of the three catalases inA. brasilense, those corresponding tokatNandkatAII are regulated by RpoH3 and RpoH5, respectively. The expression ofkatAII is regulated by a cascade of RpoE1→RpoH5 and OxyR2.IMPORTANCEIn silicoanalysis of theA. brasilensegenome showed the presence of multiple paralogs of genes involved in oxidative stress response, which included 2 OxyR transcription regulators and 3 catalases. So far,Deinococcus radioduransandVibrio choleraeare known to harbor two paralogs of OxyR, andSinorhizobium melilotiharbors three catalases. We do not yet know how the expression of multiple catalases is regulated in any bacterium. Here we show the role of multiple RpoH sigma factors and OxyR in regulating the expression of multiple catalases inA. brasilenseSp7. Our work gives a glimpse of systems biology ofA. brasilenseused for responding to oxidative stress.

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TrmB, a tRNA m7G46 methyltransferase, plays a role in hydrogen peroxide resistance and positively modulates the translation of katA and katB mRNAs in Pseudomonas aeruginosa

Nucleic Acids Research ◽

10.1093/nar/gkz702 ◽

2019 ◽

Vol 47 (17) ◽

pp. 9271-9281 ◽

Cited By ~ 5

Author(s):

Narumon Thongdee ◽

Juthamas Jaroensuk ◽

Sopapan Atichartpongkul ◽

Jurairat Chittrakanwong ◽

Kamonchanok Chooyoung ◽

...

Keyword(s):

Oxidative Stress ◽

Pseudomonas Aeruginosa ◽

Stress Response ◽

Translational Regulation ◽

Cellular Response ◽

Oxidative Stress Response ◽

Translation Efficiency ◽

Trna Modification ◽

Negative Effect

Abstract Cellular response to oxidative stress is a crucial mechanism that promotes the survival of Pseudomonas aeruginosa during infection. However, the translational regulation of oxidative stress response remains largely unknown. Here, we reveal a tRNA modification-mediated translational response to H2O2 in P. aeruginosa. We demonstrated that the P. aeruginosa trmB gene encodes a tRNA guanine (46)-N7-methyltransferase that catalyzes the formation of m7G46 in the tRNA variable loop. Twenty-three tRNA substrates of TrmB with a guanosine residue at position 46 were identified, including 11 novel tRNA substrates. We showed that loss of trmB had a strong negative effect on the translation of Phe- and Asp-enriched mRNAs. The trmB-mediated m7G modification modulated the expression of the catalase genes katA and katB, which are enriched with Phe/Asp codons at the translational level. In response to H2O2 exposure, the level of m7G modification increased, consistent with the increased translation efficiency of Phe- and Asp-enriched mRNAs. Inactivation of trmB led to decreased KatA and KatB protein abundance and decreased catalase activity, resulting in H2O2-sensitive phenotype. Taken together, our observations reveal a novel role of m7G46 tRNA modification in oxidative stress response through translational regulation of Phe- and Asp-enriched genes, such as katA and katB.

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Role of actin depolymerizing factor cofilin in Aspergillus fumigatus oxidative stress response and pathogenesis

Current Genetics ◽

10.1007/s00294-017-0777-5 ◽

2017 ◽

Vol 64 (3) ◽

pp. 619-634 ◽

Cited By ~ 3

Author(s):

Xiaodong Jia ◽

Xi Zhang ◽

Yingsong Hu ◽

Mandong Hu ◽

Shuguang Tian ◽

...

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Aspergillus Fumigatus ◽

Oxidative Stress Response ◽

Actin Depolymerizing Factor

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Reduced oxidative-stress response in red blood cells from p45NFE2-deficient mice

Blood ◽

10.1182/blood.v97.7.2151 ◽

2001 ◽

Vol 97 (7) ◽

pp. 2151-2158 ◽

Cited By ~ 34

Author(s):

Jefferson Y. Chan ◽

Mandy Kwong ◽

Margaret Lo ◽

Renee Emerson ◽

Frans A. Kuypers

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Red Blood Cells ◽

Blood Cells ◽

Leucine Zipper ◽

Oxidative Stress Response ◽

Severe Thrombocytopenia ◽

Basic Leucine Zipper ◽

Mild Anemia ◽

Expression Of Genes

Abstract p45NF-E2 is a member of the cap ‘n’ collar (CNC)-basic leucine zipper family of transcriptional activators that is expressed at high levels in various types of blood cells. Mice deficient in p45NF-E2 that were generated by gene targeting have high mortality from bleeding resulting from severe thrombocytopenia. Survivingp45nf-e2−/− adults have mild anemia characterized by hypochromic red blood cells (RBCs), reticulocytosis, and splenomegaly. Erythroid abnormalities inp45nf-e2−/− animals were previously attributed to stress erythropoiesis caused by chronic bleeding and, possibly, ineffective erythropoiesis. Previous studies suggested that CNC factors might play essential roles in regulating expression of genes that protect cells against oxidative stress. In this study, we found that p45NF-E2–deficient RBCs have increased levels of reactive oxygen species and an increased susceptibility to oxidative-stress–induced damage. Deformability of p45NF-E2–deficient RBCs was markedly reduced with oxidative stress, and mutant cells had a reduced life span. One possible reason for increased sensitivity to oxidative stress is that catalase levels were reduced in mutant RBCs. These findings suggest a role for p45NF-E2 in the oxidative-stress response in RBCs and indicate that p45NF-E2 deficiency contributes to the anemia inp45nf-e2−/− mice.

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The role of Yap1p and Skn7p-mediated oxidative stress response in the defence ofSaccharomyces cerevisiae against singlet oxygen

Yeast ◽

10.1002/yea.1392 ◽

2006 ◽

Vol 23 (10) ◽

pp. 741-750 ◽

Cited By ~ 25

Author(s):

Katrin Brombacher ◽

Beat B. Fischer ◽

Karin Rüfenacht ◽

Rik I. L. Eggen

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Singlet Oxygen ◽

Oxidative Stress Response

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Global Regulatory Impact of ClpP Protease of Staphylococcus aureus on Regulons Involved in Virulence, Oxidative Stress Response, Autolysis, and DNA Repair

Journal of Bacteriology ◽

10.1128/jb.00074-06 ◽

2006 ◽

Vol 188 (16) ◽

pp. 5783-5796 ◽

Cited By ~ 128

Author(s):

Antje Michel ◽

Franziska Agerer ◽

Christof R. Hauck ◽

Mathias Herrmann ◽

Joachim Ullrich ◽

...

Keyword(s):

Oxidative Stress ◽

Staphylococcus Aureus ◽

Dna Repair ◽

Stress Response ◽

Oxidative Stress Response ◽

Transcriptional Analysis ◽

Expression Of Genes ◽

Wide Range ◽

Genes Encoding ◽

Regulatory Impact

ABSTRACT Staphylococcus aureus is an important pathogen, causing a wide range of infections including sepsis, wound infections, pneumonia, and catheter-related infections. In several pathogens ClpP proteases were identified by in vivo expression technologies to be important for virulence. Clp proteolytic complexes are responsible for adaptation to multiple stresses by degrading accumulated and misfolded proteins. In this report clpP, encoding the proteolytic subunit of the ATP-dependent Clp protease, was deleted, and gene expression of ΔclpP was determined by global transcriptional analysis using DNA-microarray technology. The transcriptional profile reveals a strong regulatory impact of ClpP on the expression of genes encoding proteins that are involved in the pathogenicity of S. aureus and adaptation of the pathogen to several stresses. Expression of the agr system and agr-dependent extracellular virulence factors was diminished. Moreover, the loss of clpP leads to a complete transcriptional derepression of genes of the CtsR- and HrcA-controlled heat shock regulon and a partial derepression of genes involved in oxidative stress response, metal homeostasis, and SOS DNA repair controlled by PerR, Fur, MntR, and LexA. The levels of transcription of genes encoding proteins involved in adaptation to anaerobic conditions potentially regulated by an Fnr-like regulator were decreased. Furthermore, the expression of genes whose products are involved in autolysis was deregulated, leading to enhanced autolysis in the mutant. Our results indicate a strong impact of ClpP proteolytic activity on virulence, stress response, and physiology in S. aureus.

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