scholarly journals Transcription Regulation in Archaea

2016 ◽  
Vol 198 (14) ◽  
pp. 1906-1917 ◽  
Author(s):  
Alexandra M. Gehring ◽  
Julie E. Walker ◽  
Thomas J. Santangelo
Keyword(s):  
Transcription Regulation ◽  
Bacterial Species ◽  
Expression Patterns ◽  
Extreme Environments ◽  
Regulatory Mechanisms ◽  
Content Type ◽  
Archaeal Species ◽  
Archaeal Transcription

The known diversity of metabolic strategies and physiological adaptations of archaeal species to extreme environments is extraordinary. Accurate and responsive mechanisms to ensure that gene expression patterns match the needs of the cell necessitate regulatory strategies that control the activities and output of the archaeal transcription apparatus.Archaeaare reliant on a single RNA polymerase for all transcription, and many of the known regulatory mechanisms employed for archaeal transcription mimic strategies also employed for eukaryotic and bacterial species. Novel mechanisms of transcription regulation have become apparent by increasingly sophisticatedin vivoandin vitroinvestigations of archaeal species. This review emphasizes recent progress in understanding archaeal transcription regulatory mechanisms and highlights insights gained from studies of the influence of archaeal chromatin on transcription.

scholarly journals Evidence that Oxidative Stress InducesspxA2Transcription in Bacillus anthracis Sterne through a Mechanism Requiring SpxA1 and Positive Autoregulation

2016 ◽  
Vol 198 (21) ◽  
pp. 2902-2913 ◽  
Author(s):  
Skye Barendt ◽  
Cierra Birch ◽  
Lea Mbengi ◽  
Peter Zuber
Keyword(s):  
Oxidative Stress ◽  
Bacillus Anthracis ◽  
Transcription Initiation ◽  
Bacterial Species ◽  
Negative Control ◽  
Mobility Shift ◽  
Content Type ◽  
Oxidative Protein Damage

ABSTRACTBacillus anthracispossesses two paralogs of the transcriptional regulator, Spx. SpxA1 and SpxA2 interact with RNA polymerase (RNAP) to activate the transcription of genes implicated in the prevention and alleviation of oxidative protein damage. ThespxA2gene is highly upregulated in infected macrophages, but how this is achieved is unknown. Previous studies have shown that thespxA2gene was under negative control by the Rrf2 family repressor protein, SaiR, whose activity is sensitive to oxidative stress. These studies also suggested thatspxA2was under positive autoregulation. In the present study, we show byin vivoandin vitroanalyses thatspxA2is under direct autoregulation but is also dependent on the SpxA1 paralogous protein. The deletion of eitherspxA1orspxA2reduced the diamide-inducible expression of anspxA2-lacZconstruct.In vitrotranscription reactions using purifiedB. anthracisRNAP showed that SpxA1 and SpxA2 protein stimulates transcription from a DNA fragment containing thespxA2promoter. Ectopically positionedspxA2-lacZfusion requires both SpxA1 and SpxA2 for expression, but the requirement for SpxA1 is partially overcome whensaiRis deleted. Electrophoretic mobility shift assays showed that SpxA1 and SpxA2 enhance the affinity of RNAP forspxA2promoter DNA and that this activity is sensitive to reductant. We hypothesize that the previously observed upregulation ofspxA2in the oxidative environment of the macrophage is at least partly due to SpxA1-mediated SaiR repressor inactivation and the positive autoregulation ofspxA2transcription.IMPORTANCERegulators of transcription initiation are known to govern the expression of genes required for virulence in pathogenic bacterial species. Members of the Spx family of transcription factors function in control of genes required for virulence and viability in low-GC Gram-positive bacteria. InBacillus anthracis, thespxA2gene is highly induced in infected macrophages, which suggests an important role in the control of virulence gene expression during the anthrax disease state. We provide evidence that elevated concentrations of oxidized, active SpxA2 result from an autoregulatory positive-feedback loop drivingspxA2transcription.

scholarly journals Differential Gene Expression Patterns ofYersinia pestisandYersinia pseudotuberculosisduring Infection and Biofilm Formation in the Flea Digestive Tract

mSystems ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Iman Chouikha ◽  
Daniel E. Sturdevant ◽  
Clayton Jarrett ◽  
Yi-Cheng Sun ◽  
B. Joseph Hinnebusch
Keyword(s):  
Digestive Tract ◽  
Biofilm Formation ◽  
Yersinia Pseudotuberculosis ◽  
Expression Patterns ◽  
Type Vi Secretion System ◽  
Genetic Changes ◽  
Content Type ◽  
Biofilm Development

ABSTRACTYersinia pestis, the etiologic agent of plague, emerged as a fleaborne pathogen only within the last 6,000 years. Just five simple genetic changes in theYersinia pseudotuberculosisprogenitor, which served to eliminate toxicity to fleas and to enhance survival and biofilm formation in the flea digestive tract, were key to the transition to the arthropodborne transmission route. To gain a deeper understanding of the genetic basis for the development of a transmissible biofilm infection in the flea foregut, we evaluated additional gene differences and performedin vivotranscriptional profiling ofY. pestis, aY. pseudotuberculosiswild-type strain (unable to form biofilm in the flea foregut), and aY. pseudotuberculosismutant strain (able to produce foregut-blocking biofilm in fleas) recovered from fleas 1 day and 14 days after an infectious blood meal. Surprisingly, theY. pseudotuberculosismutations that increased c-di-GMP levels and enabled biofilm development in the flea did not change the expression levels of thehmsgenes responsible for the synthesis and export of the extracellular polysaccharide matrix required for mature biofilm formation. TheY. pseudotuberculosismutant uniquely expressed much higher levels ofYersiniatype VI secretion system 4 (T6SS-4) in the flea, and this locus was required for flea blockage byY. pseudotuberculosisbut not for blockage byY. pestis. Significant differences between the two species in expression of several metabolism genes, the Psa fimbrial genes, quorum sensing-related genes, transcription regulation genes, and stress response genes were evident during flea infection.IMPORTANCEY. pestisemerged as a highly virulent, arthropod-transmitted pathogen on the basis of relatively few and discrete genetic changes fromY. pseudotuberculosis. Parallel comparisons of thein vitroandin vivotranscriptomes ofY. pestisand twoY. pseudotuberculosisvariants that produce a nontransmissible infection and a transmissible infection of the flea vector, respectively, provided insights into howY. pestishas adapted to life in its flea vector and point to evolutionary changes in the regulation of metabolic and biofilm development pathways in these two closely related species.

scholarly journals Biochemical and Genetic Evidence for the Presence of Multiple Phosphatidylinositol- and Phosphatidylinositol 4,5-Bisphosphate-Specific Phospholipases C in Tetrahymena

2010 ◽  
Vol 10 (3) ◽  
pp. 412-422 ◽  
Author(s):  
George Leondaritis ◽  
Theoni Sarri ◽  
Ioannis Dafnis ◽  
Antonia Efstathiou ◽  
Dia Galanopoulou
Keyword(s):  
Biochemical Characterization ◽  
Expression Patterns ◽  
Functional Importance ◽  
Significant Similarity ◽  
Content Type ◽  
Unicellular Eukaryotes ◽  
Inositol 1,4,5 Trisphosphate ◽  
Multicellular Organisms

ABSTRACT Eukaryotic phosphoinositide-specific phospholipases C (PI-PLC) specifically hydrolyze phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P 2 ], produce the Ca 2+ -mobilizing agent inositol 1,4,5-trisphosphate, and regulate signaling in multicellular organisms. Bacterial PtdIns-specific PLCs, also present in trypanosomes, hydrolyze PtdIns and glycosyl-PtdIns, and they are considered important virulence factors. All unicellular eukaryotes studied so far contain a single PI-PLC-like gene. In this report, we show that ciliates are an exception, since we provide evidence that Tetrahymena species contain two sets of functional genes coding for both bacterial and eukaryotic PLCs. Biochemical characterization revealed two PLC activities that differ in their phosphoinositide substrate utilization, subcellular localization, secretion to extracellular space, and sensitivity to Ca 2+ . One of these activities was identified as a typical membrane-associated PI-PLC activated by low-micromolar Ca 2+ , modestly activated by GTPγS in vitro , and inhibited by the compound U73122 [1-(6-{[17β-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2,5-dione]. Importantly, inhibition of PI-PLC in vivo resulted in rapid upregulation of PtdIns(4,5)P 2 levels, suggesting its functional importance in regulating phosphoinositide turnover in Tetrahymena . By in silico and molecular analysis, we identified two PLC genes that exhibit significant similarity to bacterial but not trypanosomal PLC genes and three eukaryotic PI-PLC genes, one of which is a novel inactive PLC similar to proteins identified only in metazoa. Comparative studies of expression patterns and PI-PLC activities in three T. thermophila strains showed a correlation between expression levels and activity, suggesting that the three eukaryotic PI-PLC genes are functionally nonredundant. Our findings imply the presence of a conserved and elaborate PI-PLC-Ins(1,4,5)P 3 -Ca 2+ regulator y axis in ciliates.

scholarly journals DifferentialIn VivoGene Expression of Major Leptospira Proteins in Resistant or Susceptible Animal Models

2012 ◽  
Vol 78 (17) ◽  
pp. 6372-6376 ◽  
Author(s):  
Mariko Matsui ◽  
Marie-Estelle Soupé ◽  
Jérôme Becam ◽  
Cyrille Goarant
Keyword(s):  
Gene Expression ◽  
Animal Models ◽  
16S Rrna ◽  
Virulent Strain ◽  
Expression Patterns ◽  
Susceptible Animal ◽  
Content Type ◽  
Its Gene

ABSTRACTTranscripts ofLeptospira16S rRNA, FlaB, LigB, LipL21, LipL32, LipL36, LipL41, and OmpL37 were quantified in the blood of susceptible (hamsters) and resistant (mice) animal models of leptospirosis. We first validated adequate reference genes and then evaluated expression patternsin vivocompared toin vitrocultures. LipL32 expression was downregulatedin vivoand differentially regulated in resistant and susceptible animals. FlaB expression was also repressed in mice but not in hamsters. In contrast, LigB and OmpL37 were upregulatedin vivo. Thus, we demonstrated that a virulent strain ofLeptospiradifferentially adapts its gene expression in the blood of infected animals.

scholarly journals Role of RelA and SpoT in Burkholderia pseudomallei Virulence and Immunity

2012 ◽  
Vol 80 (9) ◽  
pp. 3247-3255 ◽  
Author(s):  
Claudia M. Müller ◽  
Laura Conejero ◽  
Natasha Spink ◽  
Matthew E. Wand ◽  
Gregory J. Bancroft ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Galleria Mellonella ◽  
Bacterial Species ◽  
Virulence Gene ◽  
Live Attenuated Vaccine ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Control And Prevention

ABSTRACTBurkholderia pseudomalleiis a Gram-negative soil bacterium and the causative agent of melioidosis, a disease of humans and animals. It is also listed as a category B bioterrorism threat agent by the U.S. Centers for Disease Control and Prevention, and there is currently no melioidosis vaccine available. Small modified nucleotides such as the hyperphosphorylated guanosine molecules ppGpp and pppGpp play an important role as signaling molecules in prokaryotes. They mediate a global stress response under starvation conditions and have been implicated in the regulation of virulence and survival factors in many bacterial species. In this study, we created arelA spoTdouble mutant inB. pseudomalleistrain K96243, which lacks (p)ppGpp-synthesizing enzymes, and investigated its phenotypein vitroandin vivo. TheB. pseudomalleiΔrelAΔspoTmutant displayed a defect in stationary-phase survival and intracellular replication in murine macrophages. Moreover, the mutant was attenuated in theGalleria mellonellainsect model and in both acute and chronic mouse models of melioidosis. Vaccination of mice with the ΔrelAΔspoTmutant resulted in partial protection against infection with wild-typeB. pseudomallei. In summary, (p)ppGpp signaling appears to represent an essential component of the regulatory network governing virulence gene expression and stress adaptation inB. pseudomallei, and the ΔrelAΔspoTmutant may be a promising live-attenuated vaccine candidate.

scholarly journals In Vivo Targeting of Clostridioides difficile Using Phage-Delivered CRISPR-Cas3 Antimicrobials

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Kurt Selle ◽  
Joshua R. Fletcher ◽  
Hannah Tuson ◽  
Daniel S. Schmitt ◽  
Lana McMillan ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Broad Spectrum ◽  
Bacterial Species ◽  
Bacterial Genome ◽  
The United States ◽  
Type I ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is an important nosocomial pathogen that causes approximately 500,000 cases of C. difficile infection (CDI) and 29,000 deaths annually in the United States. Antibiotic use is a major risk factor for CDI because broad-spectrum antimicrobials disrupt the indigenous gut microbiota, decreasing colonization resistance against C. difficile. Vancomycin is the standard of care for the treatment of CDI, likely contributing to the high recurrence rates due to the continued disruption of the gut microbiota. Thus, there is an urgent need for the development of novel therapeutics that can prevent and treat CDI and precisely target the pathogen without disrupting the gut microbiota. Here, we show that the endogenous type I-B CRISPR-Cas system in C. difficile can be repurposed as an antimicrobial agent by the expression of a self-targeting CRISPR that redirects endogenous CRISPR-Cas3 activity against the bacterial chromosome. We demonstrate that a recombinant bacteriophage expressing bacterial genome-targeting CRISPR RNAs is significantly more effective than its wild-type parent bacteriophage at killing C. difficile both in vitro and in a mouse model of CDI. We also report that conversion of the phage from temperate to obligately lytic is feasible and contributes to the therapeutic suitability of intrinsic C. difficile phages, despite the specific challenges encountered in the disease phenotypes of phage-treated animals. Our findings suggest that phage-delivered programmable CRISPR therapeutics have the potential to leverage the specificity and apparent safety of phage therapies and improve their potency and reliability for eradicating specific bacterial species within complex communities, offering a novel mechanism to treat pathogenic and/or multidrug-resistant organisms. IMPORTANCE Clostridioides difficile is a bacterial pathogen responsible for significant morbidity and mortality across the globe. Current therapies based on broad-spectrum antibiotics have some clinical success, but approximately 30% of patients have relapses, presumably due to the continued perturbation to the gut microbiota. Here, we show that phages can be engineered with type I CRISPR-Cas systems and modified to reduce lysogeny and to enable the specific and efficient targeting and killing of C. difficile in vitro and in vivo. Additional genetic engineering to disrupt phage modulation of toxin expression by lysogeny or other mechanisms would be required to advance a CRISPR-enhanced phage antimicrobial for C. difficile toward clinical application. These findings provide evidence into how phage can be combined with CRISPR-based targeting to develop novel therapies and modulate microbiomes associated with health and disease.

scholarly journals Efficacy of Aerosolized Rifaximin versus Tobramycin for Treatment ofPseudomonas aeruginosaPneumonia in Mice

2019 ◽  
Vol 63 (7) ◽  
Author(s):  
Brandon D. Kirby ◽  
Roy Al Ahmar ◽  
T. Ryan Withers ◽  
Meagan E. Valentine ◽  
Monica Valentovic ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Inhalation Therapy ◽  
Mouse Lung ◽  
Infection Model ◽  
Content Type ◽  
Dose Treatment ◽  
Alginate Production ◽  
Lung Infections

ABSTRACTPseudomonas aeruginosais a Gram-negative opportunistic bacterial pathogen that can cause chronic lung infections in patients with cystic fibrosis (CF). The current preferred treatment for CF lung infections includes inhaled tobramycin (TOB); however, studies suggest TOB cannot effectively inhibit biofilm formation. Using an NIH small compounds drug library approved for safe use in humans, we identified rifaximin (RFX), a semisynthetic, rifamycin family, nonsystemic antibiotic that inhibits alginate production and growth inP. aeruginosa. Inhibition of alginate production was further analyzed using the uronic acid carbazole assay and a promoter reporter assay that measures the transcription of the alginate biosynthetic operon. Compared to TOB, RFX significantly reduced alginate production in laboratory and CF sputum isolates ofP. aeruginosa. In addition, RFX showed a narrow range of MICs when measured with multidrug-resistant bacterial species of clinical relevance, synergistic activities with TOB or amikacin against clinical isolates, as well as reduction towardin vitropreformed biofilms. In C57BL/6 mice, penetration of nebulized TOB into the lungs was shown at a higher level than that of RFX. Further,in vivoassessment using a DBA/2 mouse lung infection model found increased survival rates with a single-dose treatment of nebulized RFX and decreasedP. aeruginosaPAO1 bioburden with a multiple-dose treatment of RFX plus TOB. In addition, mice treated with a single exposure to dimethyl sulfoxide (DMSO), a solvent that dissolves RFX, showed no apparent toxicity. In summary, RFX may be used to supplement TOB inhalation therapy to increase efficacy againstP. aeruginosabiofilm infections.

scholarly journals Increased Mortality in Mice following Immunoprophylaxis Therapy with High Dosage of Nicotinamide in Burkholderia Persistent Infections

2018 ◽  
Vol 87 (1) ◽  
Author(s):  
Sofiya N. Micheva-Viteva ◽  
Brittany N. Ross ◽  
Jun Gao ◽  
Samantha Adikari ◽  
Pengfei Zhang ◽  
...  
Keyword(s):  
Therapeutic Dose ◽  
Bacterial Infections ◽  
Response Regulator ◽  
Bacterial Species ◽  
Stringent Response ◽  
Human Neutrophils ◽  
Content Type ◽  
Efficient Reduction

ABSTRACT Bacterial persistence, known as noninherited antibacterial resistance, is a factor contributing to the establishment of long-lasting chronic bacterial infections. In this study, we examined the ability of nicotinamide (NA) to potentiate the activity of different classes of antibiotics against Burkholderia thailandensis persister cells. Here we demonstrate that addition of NA in in vitro models of B. thailandensis infection resulted in a significant depletion of the persister population in response to various classes of antibiotics. We applied microfluidic bioreactors with a continuous medium flow to study the effect of supplementation with an NA gradient on the recovery of B. thailandensis persister populations. A coculture of human neutrophils preactivated with 50 µM NA and B. thailandensis resulted in the most efficient reduction in the persister population. Applying single-cell RNA fluorescence in situ hybridization analysis and quantitative PCR, we found that NA inhibited gene expression of the stringent response regulator relA, implicated in the regulation of the persister metabolic state. We also demonstrate that a therapeutic dose of NA (250 mg/kg of body weight), previously applied as immunoprophylaxis against antibiotic-resistant bacterial species, produced adverse effects in an in vivo murine model of infection with the highly pathogenic bacterium Burkholderia pseudomallei, indicating that therapeutic dose and metabolite effects have to be carefully evaluated and tailored for every case of potential clinical application.

scholarly journals Antibiotic Degradation by Commensal Microbes Shields Pathogens

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Mergim Gjonbalaj ◽  
James W. Keith ◽  
Mytrang H. Do ◽  
Tobias M. Hohl ◽  
Eric G. Pamer ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Pathogen Resistance ◽  
Commensal Bacteria ◽  
Intestinal Lumen ◽  
Resistant Bacteria ◽  
Human Populations ◽  
Content Type ◽  
Antibiotic Degradation

ABSTRACT The complex bacterial populations that constitute the gut microbiota can harbor antibiotic resistance genes (ARGs), including those encoding β-lactamase enzymes (BLA), which degrade commonly prescribed antibiotics such as ampicillin. The prevalence of such genes in commensal bacteria has been increased in recent years by the wide use of antibiotics in human populations and in livestock. While transfer of ARGs between bacterial species has well-established dramatic public health implications, these genes can also function in trans within bacterial consortia, where antibiotic-resistant bacteria can provide antibiotic-sensitive neighbors with leaky protection from drugs, as shown both in vitro and in vivo, in models of lung and subcutaneous coinfection. However, whether the expression of ARGs by harmless commensal bacterial species can destroy antibiotics in the intestinal lumen and shield antibiotic-sensitive pathogens is unknown. To address this question, we colonized germfree or wild-type mice with a model intestinal commensal strain of Escherichia coli that produces either functional or defective BLA. Mice were subsequently infected with Listeria monocytogenes or Clostridioides difficile, followed by treatment with oral ampicillin. The production of functional BLA by commensal E. coli markedly reduced clearance of these pathogens and enhanced systemic dissemination during ampicillin treatment. Pathogen resistance was independent of ARG acquisition via horizontal gene transfer but instead relied on antibiotic degradation in the intestinal lumen by BLA. We conclude that commensal bacteria that have acquired ARGs can mediate shielding of pathogens from the bactericidal effects of antibiotics.

scholarly journals A Human Biofilm-Disrupting Monoclonal Antibody Potentiates Antibiotic Efficacy in Rodent Models of both Staphylococcus aureus and Acinetobacter baumannii Infections

2017 ◽  
Vol 61 (10) ◽  
Author(s):  
Yan Q. Xiong ◽  
Angeles Estellés ◽  
L. Li ◽  
W. Abdelhady ◽  
R. Gonzales ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Monoclonal Antibody ◽  
Acinetobacter Baumannii ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Human Monoclonal Antibody ◽  
Extracellular Dna ◽  
Content Type

ABSTRACT Many serious bacterial infections are antibiotic refractory due to biofilm formation. A key structural component of biofilm is extracellular DNA, which is stabilized by bacterial proteins, including those from the DNABII family. TRL1068 is a high-affinity human monoclonal antibody against a DNABII epitope conserved across both Gram-positive and Gram-negative bacterial species. In the present study, the efficacy of TRL1068 for the disruption of biofilm was demonstrated in vitro in the absence of antibiotics by scanning electron microscopy. The in vivo efficacy of this antibody was investigated in a well-characterized catheter-induced aortic valve infective endocarditis model in rats infected with a methicillin-resistant Staphylococcus aureus (MRSA) strain with the ability to form thick biofilms, obtained from the blood of a patient with persistent clinical infection. Animals were treated with vancomycin alone or in combination with TRL1068. MRSA burdens in cardiac vegetations and within intracardiac catheters, kidneys, spleen, and liver showed significant reductions in the combination arm versus vancomycin alone (P < 0.001). A trend toward mortality reduction was also observed (P = 0.09). In parallel, the in vivo efficacy of TRL1068 against a multidrug-resistant clinical Acinetobacter baumannii isolate was explored by using an established mouse model of skin and soft tissue catheter-related biofilm infection. Catheter segments infected with A. baumannii were implanted subcutaneously into mice; animals were treated with imipenem alone or in combination with TRL1068. The combination showed a significant reduction of catheter-adherent bacteria versus the antibiotic alone (P < 0.001). TRL1068 shows excellent promise as an adjunct to standard-of-care antibiotics for a broad range of difficult-to-treat bacterial infections.

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