scholarly journals RegAB Homolog of Burkholderia pseudomallei is the Master Regulator of Redox Control and involved in Virulence

2021 ◽  
Vol 17 (5) ◽  
pp. e1009604
Author(s):  
Julia Phenn ◽  
Jan Pané-Farré ◽  
Nikolai Meukow ◽  
Annelie Klein ◽  
Anne Troitzsch ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Regulatory Networks ◽  
Transcriptional Control ◽  
Anaerobic Growth ◽  
Infection Model ◽  
Master Regulator ◽  
Hypoxic Conditions ◽  
Mouse Infection Model ◽  
Denitrification Process

Burkholderia pseudomallei, the etiological agent of melioidosis in humans and animals, often occupies environmental niches and infection sites characterized by limited concentrations of oxygen. Versatile genomic features enable this pathogen to maintain its physiology and virulence under hypoxia, but the crucial regulatory networks employed to switch from oxygen dependent respiration to alternative terminal electron acceptors (TEA) like nitrate, remains poorly understood. Here, we combined a Tn5 transposon mutagenesis screen and an anaerobic growth screen to identify a two-component signal transduction system with homology to RegAB. We show that RegAB is not only essential for anaerobic growth, but also for full virulence in cell lines and a mouse infection model. Further investigations of the RegAB regulon, using a global transcriptomic approach, identified 20 additional regulators under transcriptional control of RegAB, indicating a superordinate role of RegAB in the B. pseudomallei anaerobiosis regulatory network. Of the 20 identified regulators, NarX/L and a FNR homolog were selected for further analyses and a role in adaptation to anaerobic conditions was demonstrated. Growth experiments identified nitrate and intermediates of the denitrification process as the likely signal activateing RegAB, NarX/L, and probably of the downstream regulators Dnr or NsrR homologs. While deletions of individual genes involved in the denitrification process demonstrated their important role in anaerobic fitness, they showed no effect on virulence. This further highlights the central role of RegAB as the master regulator of anaerobic metabolism in B. pseudomallei and that the complete RegAB-mediated response is required to achieve full virulence. In summary, our analysis of the RegAB-dependent modulon and its interconnected regulons revealed a key role for RegAB of B. pseudomallei in the coordination of the response to hypoxic conditions and virulence, in the environment and the host.

Role of prophylactic azithromycin to reduce airway inflammation and mortality in a RSV mouse infection model

2018 ◽  
Vol 53 (5) ◽  
pp. 567-574 ◽  
Author(s):  
Ricardo A. Mosquera ◽  
Wilfredo De Jesus-Rojas ◽  
James M. Stark ◽  
Aravind Yadav ◽  
Cindy K. Jon ◽  
...  
Keyword(s):  
Airway Inflammation ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Mouse Infection

scholarly journals Generation of Attenuated Mycobacterium bovis Strains by Signature-Tagged Mutagenesis for Discovery of Novel Vaccine Candidates

2005 ◽  
Vol 73 (4) ◽  
pp. 2379-2386 ◽  
Author(s):  
Desmond M. Collins ◽  
Bronwyn Skou ◽  
Stefan White ◽  
Shalome Bassett ◽  
Lauren Collins ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Bovis ◽  
Guinea Pigs ◽  
Essential Role ◽  
Immunoblot Analysis ◽  
Infection Model ◽  
Vaccine Candidates ◽  
Mouse Infection Model ◽  
Potential Vaccine

ABSTRACT Mycobacterium bovis, a member of the Mycobacterium tuberculosis complex, has a particularly wide host range and causes tuberculosis in most mammals, including humans. A signature tag mutagenesis approach, which employed illegitimate recombination and infection of guinea pigs, was applied to M. bovis to discover genes important for virulence and to find potential vaccine candidates. Fifteen attenuated mutants were identified, four of which produced no lesions when inoculated separately into guinea pigs. One of these four mutants had nine deleted genes including mmpL4 and sigK and, in guinea pigs with aerosol challenge, provided protection against tuberculosis at least equal to that of M. bovis BCG. Seven mutants had mutations near the esxA (esat-6) locus, and immunoblot analysis of these confirmed the essential role of other genes at this locus in the secretion of EsxA (ESAT-6) and EsxB (CFP10). Mutations in the eight other attenuated mutants were widely spread through the chromosome and included pks1, which is naturally inactivated in clinical strains of M. tuberculosis. Many genes identified were different from those found by signature tag mutagenesis of M. tuberculosis by use of a mouse infection model and illustrate how the use of different approaches enables identification of a wider range of attenuating mutants.

scholarly journals Conservation and novelty in the microRNA genomic landscape of hyperdiverse cichlid fishes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Peiwen Xiong ◽  
Ralf F. Schneider ◽  
C. Darrin Hulsey ◽  
Axel Meyer ◽  
Paolo Franchini
Keyword(s):  
Messenger Rna ◽  
Regulatory Networks ◽  
Transcriptional Control ◽  
Protein Coding ◽  
Adaptive Diversification ◽  
Cichlid Fishes ◽  
Novel Mirna ◽  
Genomic Landscape ◽  
Target Sites

Abstract MicroRNAs (miRNAs) play crucial roles in the post-transcriptional control of messenger RNA (mRNA). These miRNA-mRNA regulatory networks are present in nearly all organisms and contribute to development, phenotypic divergence, and speciation. To examine the miRNA landscape of cichlid fishes, one of the most species-rich families of vertebrates, we profiled the expression of both miRNA and mRNA in a diverse set of cichlid lineages. Among these, we found that conserved miRNAs differ from recently arisen miRNAs (i.e. lineage specific) in average expression levels, number of target sites, sequence variability, and physical clustering patterns in the genome. Furthermore, conserved miRNA target sites tend to be enriched at the 5′ end of protein-coding gene 3′ UTRs. Consistent with the presumed regulatory role of miRNAs, we detected more negative correlations between the expression of miRNA-mRNA functional pairs than in random pairings. Finally, we provide evidence that novel miRNA targets sites are enriched in genes involved in protein synthesis pathways. Our results show how conserved and evolutionarily novel miRNAs differ in their contribution to the genomic landscape and highlight their particular evolutionary roles in the adaptive diversification of cichlids.

scholarly journals Substituted Diphenyl Ethers as a Novel Chemotherapeutic Platform against Burkholderia pseudomallei

2013 ◽  
Vol 58 (3) ◽  
pp. 1646-1651 ◽  
Author(s):  
Jason E. Cummings ◽  
Adam J. Beaupre ◽  
Susan E. Knudson ◽  
Nina Liu ◽  
Weixuan Yu ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Ex Vivo ◽  
Infection Model ◽  
Content Type ◽  
Mouse Infection Model ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Diphenyl Ethers ◽  
Current Therapies

ABSTRACTIdentification of a novel class of anti-Burkholderiacompounds is key in addressing antimicrobial resistance to current therapies as well as naturally occurring resistance. The FabI enoyl-ACP reductase inBurkholderiais an underexploited target that presents an opportunity for development of a new class of inhibitors. A library of substituted diphenyl ethers was used to identify FabI1-specific inhibitors for assessment inBurkholderia pseudomallei ex vivoand murine efficacy models. Active FabI1 inhibitors were identified in a two-stage format consisting of percent inhibition screening and MIC determination by the broth microdilution method. Each compound was evaluated against theB. pseudomallei1026b (efflux-proficient) and Bp400 (efflux-compromised) strains.In vitroscreening identified candidate substituted diphenyl ethers that exhibited MICs of less than 1 μg/ml, and enzyme kinetic assays were used to assess potency and specificity against the FabI1 enzyme. These compounds demonstrated activity in aBurkholderia ex vivoefficacy model, and two demonstrated efficacy in an acuteB. pseudomalleimouse infection model. This work establishes substituted diphenyl ethers as a suitable platform for development of novel anti-Burkholderiacompounds that can be used for treatment of melioidosis.

scholarly journals Peptidyl-Prolyl Isomerase ppiB Is Essential for Proteome Homeostasis and Virulence in Burkholderia pseudomallei

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Nicole M. Bzdyl ◽  
Nichollas E. Scott ◽  
Isobel H. Norville ◽  
Andrew E. Scott ◽  
Timothy Atkins ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Antimicrobial Treatment ◽  
Infection Model ◽  
Virulence Determinants ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Cyclophilin B ◽  
Novel Treatments

ABSTRACT Burkholderia pseudomallei is the causative agent of melioidosis, a disease endemic to Southeast Asia and northern Australia. Mortality rates in these areas are high even with antimicrobial treatment, and there are few options for effective therapy. Therefore, there is a need to identify antibacterial targets for the development of novel treatments. Cyclophilins are a family of highly conserved enzymes important in multiple cellular processes. Cyclophilins catalyze the cis-trans isomerization of xaa-proline bonds, a rate-limiting step in protein folding which has been shown to be important for bacterial virulence. B. pseudomallei carries a putative cyclophilin B gene, ppiB, the role of which was investigated. A B. pseudomallei ΔppiB (BpsΔppiB) mutant strain demonstrates impaired biofilm formation and reduced motility. Macrophage invasion and survival assays showed that although the BpsΔppiB strain retained the ability to infect macrophages, it had reduced survival and lacked the ability to spread cell to cell, indicating ppiB is essential for B. pseudomallei virulence. This is reflected in the BALB/c mouse infection model, demonstrating the requirement of ppiB for in vivo disease dissemination and progression. Proteomic analysis demonstrates that the loss of PpiB leads to pleiotropic effects, supporting the role of PpiB in maintaining proteome homeostasis. The loss of PpiB leads to decreased abundance of multiple virulence determinants, including flagellar machinery and alterations in type VI secretion system proteins. In addition, the loss of ppiB leads to increased sensitivity toward multiple antibiotics, including meropenem and doxycycline, highlighting ppiB inhibition as a promising antivirulence target to both treat B. pseudomallei infections and increase antibiotic efficacy.

scholarly journals Two-Component Systems of Helicobacter pylori Contribute to Virulence in a Mouse Infection Model

2003 ◽  
Vol 71 (9) ◽  
pp. 5381-5385 ◽  
Author(s):  
Klaus Panthel ◽  
Patricia Dietz ◽  
Rainer Haas ◽  
Dagmar Beier
Keyword(s):  
Helicobacter Pylori ◽  
Transcriptional Control ◽  
Response Regulator ◽  
Infection Model ◽  
Histidine Kinases ◽  
Reading Frame ◽  
Mouse Infection Model ◽  
Regulatory Systems ◽  
Two Component ◽  
H Pylori

ABSTRACT Helicobacter pylori encodes three histidine kinases and five response regulators belonging to the family of two-component regulatory systems which are involved in transcriptional control. Here we demonstrate that isogenic mutants of H. pylori P76 with deletions of the response regulator open reading frame (ORF) HP1365 and ORFs HP244, HP165, and HP1364 encoding histidine kinases are unable to colonize the stomachs of BALB/c mice, suggesting an essential role of these systems in the regulation of important virulence properties of H. pylori. Furthermore, we demonstrate that the genes under the control of the PHP1408 and PHP119 promoters which are regulated by the two-component system HP166-HP165 are not essential for single mutant colonization of mice but are required under competitive colonization conditions.

scholarly journals Periplasmic Superoxide Dismutase in Meningococcal Pathogenicity

1998 ◽  
Vol 66 (1) ◽  
pp. 213-217 ◽  
Author(s):  
Kathryn E. Wilks ◽  
Kate L. R. Dunn ◽  
Jayne L. Farrant ◽  
Karen M. Reddin ◽  
Andrew R. Gorringe ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Free Radicals ◽  
Superoxide Radical ◽  
Infection Model ◽  
Wild Type ◽  
Superoxide Radical Anion ◽  
Mouse Infection Model ◽  
Increased Sensitivity ◽  
Hydroxyl Free Radicals

ABSTRACT Meningococcal sodC encodes periplasmic copper- and zinc-cofactored superoxide dismutase (Cu,Zn SOD) which catalyzes the conversion of the superoxide radical anion to hydrogen peroxide, preventing a sequence of reactions leading to production of toxic hydroxyl free radicals. From its periplasmic location, Cu,Zn SOD was inferred to acquire its substrate from outside the bacterial cell and was speculated to play a role in preserving meningococci from the action of microbicidal oxygen free radicals produced in the context of host defense. A sodC mutant was constructed by allelic exchange and was used to investigate the role of Cu,Zn SOD in pathogenicity. Wild-type and mutant meningococci grew at comparable rates and survived equally long in aerobic liquid culture. The mutant showed no increased sensitivity to paraquat, which generates superoxide within the cytosol, but was approximately 1,000-fold more sensitive to the toxicity of superoxide generated in solution by the xanthine/xanthine oxidase system. These data support a role for meningococcal Cu,Zn SOD in protection against exogenous superoxide. In experiments to translate this into a role in pathogenicity, wild-type and mutant organisms were used in an intraperitoneal mouse infection model. The sodC mutant was significantly less virulent. We conclude that periplasmic Cu,Zn SOD contributes to the virulence ofNeisseria meningitidis, most likely by reducing the effectiveness of toxic oxygen host defenses.

scholarly journals Listeria monocytogenes requires cellular respiration for NAD+ regeneration and pathogenesis

2021 ◽  
Author(s):  
Rafael Rivera-Lugo ◽  
David Deng ◽  
Andrea Anaya-Sanchez ◽  
Sara Tejedor-Sanz ◽  
Valeria M Reyes Ruiz ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Oxidative Phosphorylation ◽  
Nadh Oxidase ◽  
Cellular Respiration ◽  
Bacterial Respiration ◽  
Infection Model ◽  
Primary Role ◽  
Growth Defects ◽  
Mouse Infection Model

Cellular respiration is essential for multiple bacterial pathogens and a validated antibiotic target. In addition to driving oxidative phosphorylation, bacterial respiration has a variety of ancillary functions that obscure its contribution to pathogenesis. We find here that the intracellular pathogen Listeria monocytogenes encodes two respiratory pathways which are partially functionally redundant and indispensable for pathogenesis. Loss of respiration decreased NAD+ regeneration, but this could be specifically reversed by heterologous expression of a water-forming NADH oxidase (NOX). NOX expression fully rescued intracellular growth defects and increased L. monocytogenes loads >1,000-fold in a mouse infection model. Consistent with NAD+ regeneration maintaining L. monocytogenes viability and enabling immune evasion, a respiration-deficient strain exhibited elevated bacteriolysis within the host cytosol and NOX rescued this phenotype. These studies show that NAD+ regeneration, rather than oxidative phosphorylation, represents the primary role of L. monocytogenes respiration and highlight the nuanced relationship between bacterial metabolism, physiology, and pathogenesis.

scholarly journals Characterization of the Burkholderia pseudomallei K96243 Capsular Polysaccharide I Coding Region

2012 ◽  
Vol 80 (3) ◽  
pp. 1209-1221 ◽  
Author(s):  
Jon Cuccui ◽  
Timothy S. Milne ◽  
Nicholas Harmer ◽  
Alison J. George ◽  
Sarah V. Harding ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Capsular Polysaccharide ◽  
Bioinformatic Analysis ◽  
Chromosome 1 ◽  
Infection Model ◽  
Coding Region ◽  
Content Type ◽  
Group 3

Burkholderia pseudomalleiis the causative agent of melioidosis, a disease endemic to regions of Southeast Asia and Northern Australia. Both humans and a range of other animal species are susceptible to melioidosis, and the production of a group 3 polysaccharide capsule inB. pseudomalleiis essential for virulence.B. pseudomalleicapsular polysaccharide (CPS) I comprises unbranchedmanno-heptopyranose residues and is encoded by a 34.5-kb locus on chromosome 1. Despite the importance of this locus, the role of all of the genes within this region is unclear. We inactivated 18 of these genes and analyzed their phenotype using Western blotting and immunofluorescence staining. Furthermore, by combining this approach with bioinformatic analysis, we were able to develop a model for CPS I biosynthesis and export. We report that inactivatinggmhA,wcbJ, andwcbNinB. pseudomalleiK96243 retains the immunogenic integrity of the polysaccharide despite causing attenuation in the BALB/c murine infection model. Mice immunized with theB. pseudomalleiK96243 mutants lacking a functional copy of eithergmhAorwcbJwere afforded significant levels of protection against a wild-typeB. pseudomalleiK96243 challenge.

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