scholarly journals The oxidative stress response of pathogenic Leptospira is controlled by two peroxide stress regulators which putatively cooperate in controlling virulence

2021 ◽  
Vol 17 (12) ◽  
pp. e1009087 ◽  
Author(s):  
Crispin Zavala-Alvarado ◽  
Samuel G. Huete ◽  
Antony T. Vincent ◽  
Odile Sismeiro ◽  
Rachel Legendre ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Transcriptional Control ◽  
Phylogenetic Analyses ◽  
Amino Acid Residues ◽  
Pathogenic Leptospira ◽  
Non Coding Rna ◽  
Genes Encoding ◽  
Causative Agents ◽  
Life Threatening ◽  
Peroxide Stress

Pathogenic Leptospira are the causative agents of leptospirosis, the most widespread zoonotic infectious disease. Leptospirosis is a potentially severe and life-threatening emerging disease with highest burden in sub-tropical areas and impoverished populations. Mechanisms allowing pathogenic Leptospira to survive inside a host and induce acute leptospirosis are not fully understood. The ability to resist deadly oxidants produced by the host during infection is pivotal for Leptospira virulence. We have previously shown that genes encoding defenses against oxidants in L. interrogans are repressed by PerRA (encoded by LIMLP_10155), a peroxide stress regulator of the Fur family. In this study, we describe the identification and characterization of another putative PerR-like regulator (LIMLP_05620) in L. interrogans. Protein sequence and phylogenetic analyses indicated that LIMLP_05620 displayed all the canonical PerR amino acid residues and is restricted to pathogenic Leptospira clades. We therefore named this PerR-like regulator PerRB. In L. interrogans, the PerRB regulon is distinct from that of PerRA. While a perRA mutant had a greater tolerance to peroxide, inactivating perRB led to a higher tolerance to superoxide, suggesting that these two regulators have a distinct function in the adaptation of L. interrogans to oxidative stress. The concomitant inactivation of perRA and perRB resulted in a higher tolerance to both peroxide and superoxide and, unlike the single mutants, a double perRAperRB mutant was avirulent. Interestingly, this correlated with major changes in gene and non-coding RNA expression. Notably, several virulence-associated genes (clpB, ligA/B, and lvrAB) were repressed. By obtaining a double mutant in a pathogenic Leptospira strain, our study has uncovered an interplay of two PerRs in the adaptation of Leptospira to oxidative stress with a putative role in virulence and pathogenicity, most likely through the transcriptional control of a complex regulatory network.

scholarly journals The oxidative stress response and virulence of pathogenic Leptospira are controlled by the interplay of two peroxide stress regulators

2020 ◽  
Author(s):  
Crispin Zavala-Alvarado ◽  
Antony T. Vincent ◽  
Odile Sismeiro ◽  
Rachel Legendre ◽  
Hugo Varet ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Infectious Disease ◽  
Regulatory Network ◽  
Phylogenetic Analyses ◽  
Emerging Disease ◽  
Pathogenic Leptospira ◽  
Causative Agents ◽  
Tropical Areas ◽  
Complex Regulatory Network ◽  
Peroxide Stress

AbstractPathogenic Leptospira are the causative agents of leptospirosis, the most widespread zoonotic infectious disease. Leptospirosis is a potentially severe and life-threatening emerging disease with highest burden in sub-tropical areas and impoverish populations. Mechanisms allowing pathogenic Leptospira to survive inside a host and induce acute leptospirosis are not fully understood. The ability to resist deadly oxidants produced by the host during infection is pivotal for Leptospira virulence. We have previously shown that genes encoding defenses against oxidants in L. interrogans are repressed by PerRA (encoded by LIMLP_10155), a peroxide stress regulator of the Fur family. In this study, we describe the identification and characterization of another putative PerR-like regulator (LIMLP_05620) in L. interrogans. Protein sequence and phylogenetic analyses indicated that LIMLP_05620 displayed all the canonical PerR amino acid residues and is restricted to pathogenic Leptospira clades. We therefore named this PerR-like regulator PerRB. In L. interrogans, the PerRB regulon is distinct from that of PerRA. While a perRA mutant had a greater tolerance to peroxide, inactivating perRB led to a higher tolerance to superoxide, suggesting that these two regulators have a distinct function in the adaptation of L. interrogans to oxidative stress. The concomitant inactivation of perRA and perRB resulted in a higher tolerance to both peroxide and superoxide and, unlike the single mutants, to the loss of Leptospira virulence. Interestingly, this correlated with major changes in gene and non-coding RNA expression, only observed in the double perRAperRB mutant. Notably, several virulence-associated genes (clpB, ligA/B, and lvrAB) were repressed. By obtaining the first double mutant in a pathogenic Leptospira strain, our study has uncovered for the first time the interplay of two PerRs, not only in the adaptation of Leptospira to oxidative stress, but also in their virulence and pathogenicity, most likely through the transcriptional control of a complex regulatory network.Author summaryLeptospirosis is a widespread infectious disease responsible for over one million of severe cases and 60 000 fatalities annually worldwide. This neglected and emerging disease has a worldwide distribution, but it mostly affects populations from developing countries in sub-tropical areas. The causative agents of leptospirosis are pathogenic bacterial Leptospira spp. There is a considerable deficit in our knowledge of these atypical bacteria, including their virulence mechanisms. In addition to the Leptospira PerRA regulator that represses defenses against peroxide, we have identified and characterized a second PerR regulator in pathogenic Leptospira species (PerRB) that participates in Leptospira tolerance to superoxide. Phenotypic and transcriptomic analyses of single PerRA and PerRB mutants suggest that the two PerRs fulfill distinct functions in the adaptation to oxidative stress. However, concomitant inactivation of PerRA and PerRB resulted in a higher tolerance to both peroxide and superoxide, but to a loss virulence.The absence of the two PerR regulators resulted in global and major changes in the transcriptional profile, including a dramatic decrease of several virulence factor expression. Our study has demonstrated that PerRA and PerRB cooperate to orchestrate a complex regulatory network involved in Leptospira virulence.

scholarly journals Schistosoma mansoni α-N-acetylgalactosaminidase (SmNAGAL) regulates coordinated parasite movement and egg production

2022 ◽  
Vol 18 (1) ◽  
pp. e1009828
Author(s):  
Benjamin J. Hulme ◽  
Kathrin K. Geyer ◽  
Josephine E. Forde-Thomas ◽  
Gilda Padalino ◽  
Dylan W. Phillips ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Egg Production ◽  
Phylogenetic Analyses ◽  
Significant Inhibition ◽  
Amino Acid Residues ◽  
Glycosyl Hydrolases ◽  
Host Interactions ◽  
Human Genes ◽  
Genes Encoding ◽  
Parenchymal Cells

α-galactosidase (α-GAL) and α-N-acetylgalactosaminidase (α-NAGAL) are two glycosyl hydrolases responsible for maintaining cellular homeostasis by regulating glycan substrates on proteins and lipids. Mutations in the human genes encoding either enzyme lead to neurological and neuromuscular impairments seen in both Fabry- and Schindler/Kanzaki- diseases. Here, we investigate whether the parasitic blood fluke Schistosoma mansoni, responsible for the neglected tropical disease schistosomiasis, also contains functionally important α-GAL and α-NAGAL proteins. As infection, parasite maturation and host interactions are all governed by carefully-regulated glycosylation processes, inhibiting S. mansoni’s α-GAL and α-NAGAL activities could lead to the development of novel chemotherapeutics. Sequence and phylogenetic analyses of putative α-GAL/α-NAGAL protein types showed Smp_089290 to be the only S. mansoni protein to contain the functional amino acid residues necessary for α-GAL/α-NAGAL substrate cleavage. Both α-GAL and α-NAGAL enzymatic activities were higher in females compared to males (p<0.05; α-NAGAL > α-GAL), which was consistent with smp_089290’s female biased expression. Spatial localisation of smp_089290 revealed accumulation in parenchymal cells, neuronal cells, and the vitellaria and mature vitellocytes of the adult schistosome. siRNA-mediated knockdown (>90%) of smp_089290 in adult worms significantly inhibited α-NAGAL activity when compared to control worms (siLuc treated males, p<0.01; siLuc treated females, p<0.05). No significant reductions in α-GAL activities were observed in the same extracts. Despite this, decreases in α-NAGAL activities correlated with a significant inhibition in adult worm motility as well as in egg production. Programmed CRISPR/Cas9 editing of smp_089290 in adult worms confirmed the egg reduction phenotype. Based on these results, Smp_089290 was determined to act predominantly as an α-NAGAL (hereafter termed SmNAGAL) in schistosome parasites where it participates in coordinating movement and oviposition processes. Further characterisation of SmNAGAL and other functionally important glycosyl hydrolases may lead to the development of a novel anthelmintic class of compounds.

scholarly journals The adaptive transcriptional response of pathogenic Leptospira to peroxide reveals new defenses against infection-related oxidative stress

2020 ◽  
Author(s):  
Crispin Zavala-Alvarado ◽  
Odile Sismeiro ◽  
Rachel Legendre ◽  
Hugo Varet ◽  
Giovanni Bussotti ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Adaptive Response ◽  
Sigma Factors ◽  
Component Systems ◽  
Two Component ◽  
Genes Encoding ◽  
Causative Agents ◽  
Two Component Systems ◽  
Non Coding Rnas ◽  
Insight Into

AbstractPathogenic Leptospira spp. are the causative agents of the waterborne zoonotic disease leptospirosis. During infection, Leptospira are confronted with dramatic adverse environmental changes such as deadly reactive oxygen species (ROS). Withstanding ROS produced by the host innate immunity is an important strategy evolved by pathogenic Leptospira for persisting in and colonizing hosts. In L. interrogans, genes encoding defenses against ROS are repressed by the peroxide stress regulator, PerR. In this study, RNA sequencing was performed to characterize both the L. interrogans adaptive response to low and high concentrations of hydrogen peroxide and the PerR regulon. We showed that Leptospira solicit three main peroxidase machineries (catalase, cytochrome C peroxidase and peroxiredoxin) and heme to detoxify oxidants produced during a peroxide stress. In addition, canonical molecular chaperones of the heat shock response and DNA repair proteins from the SOS response were required for Leptospira recovering from oxidative damages. Determining the PerR regulon allowed to identify the PerR-dependent mechanisms of the peroxide adaptive response and has revealed a PerR-independent regulatory network involving other transcriptional regulators, two-component systems and sigma factors as well as non-coding RNAs that putatively orchestrate, in concert with PerR, this adaptive response. In addition, we have identified other PerR-regulated genes encoding a TonB-dependent transport system, a lipoprotein (LipL48) and a two-component system (VicKR) involved in Leptospira tolerance to superoxide and that could represent the first defense mechanism against superoxide in L. interrogans, a bacterium lacking canonical superoxide dismutase. Our findings provide a comprehensive insight into the mechanisms required by pathogenic Leptospira to overcome infection-related oxidants during the arm race with a host. This will participate in framing future hypothesis-driven studies to identify and decipher novel virulence mechanisms in this life-threatening pathogen.Author summaryLeptospirosis is a zoonotic infectious disease responsible for over one million of severe cases and 60 000 fatalities annually worldwide. This neglected and emerging disease has a worldwide distribution, but it mostly affects populations from developing countries in sub-tropical areas. The causative agents of leptospirosis are pathogenic bacterial Leptospira spp. There is a considerable deficit in our knowledge of these atypical bacteria, including their virulence mechanisms. During infection, Leptospira are confronted with the deadly oxidants produced by the host tissues and immune response. Here, we have identified the cellular factors necessary for Leptospira to overcome the oxidative stress response. We found that Leptospira solicit peroxidases to detoxify oxidants as well as chaperones of the heat shock response and DNA repair proteins of the SOS response to recover from oxidative damage. Moreover, our study indicates that adaptation to oxidative stress is orchestrated by a regulatory network involving PerR and other transcriptional regulators, sigma factors, two component systems, and putative non-coding RNAs. These findings provide a comprehensive insight into the mechanisms required by pathogenic Leptospira to tolerate infection-related oxidants, helping identify novel virulence factors, developing new therapeutic targets and vaccines against leptospirosis.

scholarly journals Schistosoma mansoni α-N-acetylgalactosaminidase (SmNAGAL) regulates coordinated parasite movement and egg production

2021 ◽  
Author(s):  
Benjamin Hulme ◽  
Kathrin Geyer ◽  
Josephine Forde-Thomas ◽  
Gilda Padalino ◽  
Dylan Phillips ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Egg Production ◽  
Phylogenetic Analyses ◽  
Significant Inhibition ◽  
Amino Acid Residues ◽  
Glycosyl Hydrolases ◽  
Host Interactions ◽  
Human Genes ◽  
Genes Encoding ◽  
Parenchymal Cells

α-galactosidase (α-GAL) and α-N-acetylgalactosaminidase (α-NAGAL) are two glycosyl hydrolases responsible for maintaining cellular homeostasis by regulating glycan substrates on proteins and lipids. Mutations in the human genes encoding either enzyme lead to neurological and neuromuscular impairments seen in both Fabry- and Schindler/Kanzaki- diseases. Here, we investigate whether the parasitic blood fluke Schistosoma mansoni, responsible for the neglected tropical disease schistosomiasis, also contains functionally important α-GAL and α-NAGAL proteins. As infection, parasite maturation and host interactions are all governed by carefully-regulated glycosylation processes, inhibiting S. mansoni’s α-GAL and α-NAGAL activities could lead to the development of novel chemotherapeutics. Sequence and phylogenetic analyses of putative α-GAL/α-NAGAL protein types showed Smp_089290 to be the only S. mansoni protein to contain the functional amino acid residues necessary for α-GAL/α-NAGAL substrate cleavage. Both α-GAL and α-NAGAL enzymatic activities were higher in females compared to males (p<0.05; α-NAGAL > α-GAL), which was consistent with smp_089290’s female biased expression. Spatial localisation of smp_089290 revealed accumulation in parenchymal cells, neuronal cells, and the vitellaria and mature vitellocytes of the adult schistosome. siRNA-mediated knockdown (>90%) of smp_089290 in adult worms significantly inhibited α-NAGAL activity when compared to control worms (siLuc treated males, p<0.01; siLuc treated females, p<0.05). No significant reductions in α-GAL activities were observed in the same extracts. Despite this, decreases in α-NAGAL activities correlated with a significant inhibition in adult worm motility as well as in egg production. Programmed CRISPR/Cas9 editing of smp_089290 in adult worms confirmed the egg reduction phenotype. Based on these results, Smp_089290 was determined to act predominantly as an α-NAGAL (hereafter termed SmNAGAL) in schistosome parasites where it participates in coordinating movement and oviposition processes. Pharmacological inhibition of SmNAGAL may lead to the development of a novel anthelmintic class of compounds.

scholarly journals Aerotolerance and Peroxide Resistance in Peroxidase and PerR Mutants of Streptococcus pyogenes

2000 ◽  
Vol 182 (19) ◽  
pp. 5290-5299 ◽  
Author(s):  
Katherine Y. King ◽  
Joshua A. Horenstein ◽  
Michael G. Caparon
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Pyogenes ◽  
Cumene Hydroperoxide ◽  
Wild Type ◽  
Resistance Response ◽  
Aerobic Conditions ◽  
Genes Encoding ◽  
Sublethal Doses ◽  
Alkyl Hydroperoxidase ◽  
Peroxide Stress

ABSTRACT Survival in aerobic conditions is critical to the pathogenicity of many bacteria. To investigate the means of aerotolerance and resistance to oxidative stress in the catalase-negative organismStreptococcus pyogenes, we used a genomics-based approach to identify and inactivate homologues of two peroxidase genes, encoding alkyl hydroperoxidase (ahpC) and glutathione peroxidase (gpoA). Single and double mutants survived as well as the wild type under aerobic conditions. However, they were more susceptible than the wild type to growth suppression by paraquat and cumene hydroperoxide. In addition, we show that S. pyogenesdemonstrates an inducible peroxide resistance response when treated with sublethal doses of peroxide. This resistance response was intact in ahpC and gpoA mutants but not in mutants lacking PerR, a repressor of several genes including ahpCand catalase (katA) in Bacillus subtilis. Because our data indicate that these peroxidase genes are not essential for aerotolerance or induced resistance to peroxide stress in S. pyogenes, genes for a novel mechanism of managing peroxide stress may be regulated by PerR in streptococci.

scholarly journals The Early Transcriptional Response of Human Granulocytes to Infection with Candida albicans Is Not Essential for Killing but Reflects Cellular Communications

2006 ◽  
Vol 75 (3) ◽  
pp. 1493-1501 ◽  
Author(s):  
Chantal Fradin ◽  
Abigail L. Mavor ◽  
Günther Weindl ◽  
Martin Schaller ◽  
Karin Hanke ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Mononuclear Cells ◽  
De Novo ◽  
Transcriptional Response ◽  
Mononuclear Leukocytes ◽  
General Notion ◽  
Genes Encoding ◽  
Global Transcriptional Profile ◽  
Life Threatening ◽  
Systemic Infections

ABSTRACT Candida albicans is a polymorphic opportunistic fungus that can cause life-threatening systemic infections following hematogenous dissemination in patients susceptible to nosocomial infection. Neutrophils form part of the innate immune response, which is the first line of defense against microbes and is particularly important in C. albicans infections. To compare the transcriptional response of leukocytes exposed to C. albicans, we investigated the expression of key cytokine genes in polymorphonuclear and mononuclear leukocytes after incubation with C. albicans for 1 h. Isolated mononuclear cells expressed high levels of genes encoding proinflammatory signaling molecules, whereas neutrophils exhibited much lower levels, similar to those observed in whole blood. The global transcriptional profile of neutrophils was examined by using an immunology-biased human microarray to determine whether different morphological forms or the viability of C. albicans altered the transcriptome. Hyphal cells appeared to have the broadest effect, although the most strongly induced genes were regulated independently of morphology or viability. These genes were involved in proinflammatory cell-cell signaling, cell signal transduction, and cell growth. Generally, genes encoding known components of neutrophil granules showed no upregulation at this time point; however, lactoferrin, a well-known candidacidal peptide, was secreted by neutrophils. Addition to inhibitors of RNA or protein de novo synthesis did not influence the killing activity within 30 min. These results support the general notion that neutrophils do not require gene transcription to mount an immediate and direct attack against microbes. However, neutrophils exposed to C. albicans express genes involved in communication with other immune cells.

scholarly journals Genome-Wide Identification of Francisella tularensis Virulence Determinants

2007 ◽  
Vol 75 (6) ◽  
pp. 3089-3101 ◽  
Author(s):  
Jingliang Su ◽  
Jun Yang ◽  
Daimin Zhao ◽  
Thomas H. Kawula ◽  
Jeffrey A. Banas ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Stress Responses ◽  
Small Subset ◽  
Virulence Determinants ◽  
Genome Wide ◽  
Genes Encoding ◽  
Capsule Locus ◽  
Life Threatening ◽  
Transposon Mutants ◽  
Schu S4

ABSTRACT Francisella tularensis is a gram-negative pathogen that causes life-threatening infections in humans and has potential for use as a biological weapon. The genetic basis of the F. tularensis virulence is poorly understood. This study screened a total of 3,936 transposon mutants of the live vaccine strain for infection in a mouse model of respiratory tularemia by signature-tagged mutagenesis. We identified 341 mutants attenuated for infection in the lungs. The transposon disruptions were mapped to 95 different genes, virtually all of which are also present in the genomes of other F. tularensis strains, including human pathogenic F. tularensis strain Schu S4. A small subset of these attenuated mutants carried insertions in the genes encoding previously known virulence factors, but the majority of the identified genes have not been previously linked to F. tularensis virulence. Among these are genes encoding putative membrane proteins, proteins associated with stress responses, metabolic proteins, transporter proteins, and proteins with unknown functions. Several attenuated mutants contained disruptions in a putative capsule locus which partially resembles the poly-γ-glutamate capsule biosynthesis locus of Bacillus anthracis, the anthrax agent. Deletional mutation analysis confirmed that this locus is essential for F. tularensis virulence.

scholarly journals Physiological Regulation of G Protein-Linked Signaling

1999 ◽  
Vol 79 (4) ◽  
pp. 1373-1430 ◽  
Author(s):  
Andrew J. Morris ◽  
Craig C. Malbon
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Chemokine Receptors ◽  
Transcriptional Control ◽  
Heterotrimeric G Proteins ◽  
Protein Prenylation ◽  
Physiological Control ◽  
Physiological Regulation ◽  
Surface Receptors ◽  
Genes Encoding

Heterotrimeric G proteins in vertebrates constitute a family molecular switches that transduce the activation of a populous group of cell-surface receptors to a group of diverse effector units. The receptors include the photopigments such as rhodopsin and prominent families such as the adrenergic, muscarinic acetylcholine, and chemokine receptors involved in regulating a broad spectrum of responses in humans. Signals from receptors are sensed by heterotrimeric G proteins and transduced to effectors such as adenylyl cyclases, phospholipases, and various ion channels. Physiological regulation of G protein-linked receptors allows for integration of signals that directly or indirectly effect the signaling from receptor→G protein→effector(s). Steroid hormones can regulate signaling via transcriptional control of the activities of the genes encoding members of G protein-linked pathways. Posttranscriptional mechanisms are under physiological control, altering the stability of preexisting mRNA and affording an additional level for regulation. Protein phosphorylation, protein prenylation, and proteolysis constitute major posttranslational mechanisms employed in the physiological regulation of G protein-linked signaling. Drawing upon mechanisms at all three levels, physiological regulation permits integration of demands placed on G protein-linked signaling.

scholarly journals The pentose phosphate pathway in Trypanosoma cruzi: a potential target for the chemotherapy of Chagas disease

2007 ◽  
Vol 79 (4) ◽  
pp. 649-663 ◽  
Author(s):  
Mariana Igoillo-Esteve ◽  
Dante Maugeri ◽  
Ana L. Stern ◽  
Paula Beluardi ◽  
Juan J. Cazzulo
Keyword(s):  
Oxidative Stress ◽  
Trypanosoma Cruzi ◽  
Pentose Phosphate Pathway ◽  
Single Copy ◽  
Pentose Phosphate ◽  
Site Directed Mutagenesis ◽  
Haploid Genome ◽  
Salt Bridges ◽  
Phosphogluconate Dehydrogenase ◽  
Genes Encoding

Trypanosoma cruzi is highly sensitive to oxidative stress caused by reactive oxygen species. Trypanothione, the parasite's major protection against oxidative stress, is kept reduced by trypanothione reductase, using NADPH; the major source of the reduced coenzyme seems to be the pentose phosphate pathway. Its seven enzymes are present in the four major stages in the parasite's biological cycle; we have cloned and expressed them in Escherichia coli as active proteins. Glucose 6-phosphate dehydrogenase, which controls glucose flux through the pathway by its response to the NADP/NADPH ratio, is encoded by a number of genes per haploid genome, and is induced up to 46-fold by hydrogen peroxide in metacyclic trypomastigotes. The genes encoding 6-phosphogluconolactonase, 6-phosphogluconate dehydrogenase, transaldolase and transketolase are present in the CL Brener clone as a single copy per haploid genome. 6-phosphogluconate dehydrogenase is very unstable, but was stabilized introducing two salt bridges by site-directed mutagenesis. Ribose-5-phosphate isomerase belongs to Type B; genes encoding Type A enzymes, present in mammals, are absent. Ribulose-5-phosphate epimerase is encoded by two genes. The enzymes of the pathway have a major cytosolic component, although several of them have a secondary glycosomal localization, and also minor localizations in other organelles.

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