Serum-Mediated Cleavage ofBacillus anthracisProtective Antigen Is a Two-Step Process That Involves a Serum Carboxypeptidase

ABSTRACTMuch of our understanding of the activity of anthrax toxin is based onin vitrosystems, which delineate the interaction betweenBacillus anthracistoxins and the cell surface. However, these systems fail to account for the intimate association ofB. anthraciswith the circulatory system, including the contribution of serum proteins to the host response and processing of anthrax toxins. Using a variety of immunological techniques to inhibit serum processing ofB. anthracisprotective antigen (PA) along with mass spectrometry analysis, we demonstrate that serum digests PA via 2 distinct reactions. In the first reaction, serum cleaves PA83into 2 fragments to produce PA63and PA20fragments, similarly to that observed following furin digestion. This is followed by carboxypeptidase-mediated removal of the carboxy-terminal arginine and lysines from PA20.IMPORTANCEOur findings identify a serum-mediated modification of PA20that has not been previously described. These observations further imply that the processing of PA is more complex than currently thought. Additional study is needed to define the contribution of serum processing of PA to the host response and individual susceptibility to anthrax.

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Serum-mediated cleavage ofBacillus anthracisProtective Antigen is a two-step process that involves a serum carboxypeptidase

10.1101/267369 ◽

2018 ◽

Author(s):

David L. Goldman ◽

Edward Nieves ◽

Antonio Nakouzi ◽

Johanna Rivera ◽

Ei Ei Phyu ◽

...

Keyword(s):

Protective Antigen ◽

Serum Proteins ◽

Circulatory System ◽

Mass Spectrometry Analysis ◽

Spectrometry Analysis ◽

Intimate Association ◽

Lysine Residues ◽

Anthrax Toxins ◽

Carboxy Terminal

AbstractMuch our understanding of the activity of anthrax toxin is based onin-vitrosystems, which delineate the interaction betweenB. anthracistoxins and the cell surface. These systems however, fail to account for the intimate association ofB. anthraciswith the circulatory system, including the contribution of serum proteins to the host response and processing of anthrax toxins. Using variety immunologic techniques to inhibit serum processing ofB. anthracisProtective Antigen (PA) along with mass spectrometry analysis, we demonstrate that serum digests PA via 2 distinct reactions. In the first reaction, serum cleaves PA83into 2 fragments to produce PA63and PA20fragments, similar to that observed following furin digestion. This is followed by carboxypeptidase-mediated removal of the carboxy-terminal arginine and lysine residues from PA20.

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Thiol Peroxidase Is an Important Component of Streptococcus pneumoniae in Oxygenated Environments

Infection and Immunity ◽

10.1128/iai.00126-12 ◽

2012 ◽

Vol 80 (12) ◽

pp. 4333-4343 ◽

Cited By ~ 32

Author(s):

Barak Hajaj ◽

Hasan Yesilkaya ◽

Rachel Benisty ◽

Maayan David ◽

Peter W. Andrew ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Mass Spectrometry Analysis ◽

Activity Levels ◽

Content Type ◽

Spectrometry Analysis ◽

Cellular Processes ◽

Thiol Peroxidase ◽

Fine Tune

ABSTRACTStreptococcus pneumoniaeis an aerotolerant Gram-positive bacterium that causes an array of diseases, including pneumonia, otitis media, and meningitis. During aerobic growth,S. pneumoniaeproduces high levels of H2O2. SinceS. pneumoniaelacks catalase, the question of how it controls H2O2levels is of critical importance. Thepsalocus encodes an ABC Mn2+-permease complex (psaBCA) and a putative thiol peroxidase,tpxD. This study shows thattpxDencodes a functional thiol peroxidase involved in the adjustment of H2O2homeostasis in the cell. Kinetic experiments showed that recombinant TpxD removed H2O2efficiently. However,in vivoexperiments revealed that TpxD detoxifies only a fraction of the H2O2generated by the pneumococcus. Mass spectrometry analysis demonstrated that TpxD Cys58undergoes selective oxidationin vivo, under conditions where H2O2is formed, confirming the thiol peroxidase activity. Levels of TpxD expression and synthesisin vitrowere significantly increased in cells grown under aerobic versus anaerobic conditions. The challenge with D39 and TIGR4 with H2O2resulted intpxDupregulation, whilepsaBCAexpression was oppositely affected. However, the challenge of ΔtpxDmutants with H2O2did not affectpsaBCA, implying that TpxD is involved in the regulation of thepsaoperon, in addition to its scavenging activity. Virulence studies demonstrated a notable difference in the survival time of mice infected intranasally with D39 compared to that of mice infected intranasally with D39ΔtpxD. However, when bacteria were administered directly into the blood, this difference disappeared. The findings of this study suggest that TpxD constitutes a component of the organism's fundamental strategy to fine-tune cellular processes in response to H2O2.

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Nonribosomal Peptide Synthetase GenespesLandpes1Are Essential for Fumigaclavine C Production in Aspergillus fumigatus

Applied and Environmental Microbiology ◽

10.1128/aem.07249-11 ◽

2012 ◽

Vol 78 (9) ◽

pp. 3166-3176 ◽

Cited By ~ 33

Author(s):

Karen A. O'Hanlon ◽

Lorna Gallagher ◽

Markus Schrettl ◽

Christoph Jöchl ◽

Kevin Kavanagh ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Opportunistic Pathogen ◽

Mass Spectrometry Analysis ◽

Infection Model ◽

Nonribosomal Peptide ◽

Content Type ◽

Spectrometry Analysis ◽

Peptide Synthetases ◽

Increased Sensitivity

ABSTRACTThe identity of metabolites encoded by the majority of nonribosomal peptide synthetases in the opportunistic pathogen,Aspergillus fumigatus, remains outstanding. We found that the nonribosomal peptide (NRP) synthetases PesL and Pes1 were essential for fumigaclavine C biosynthesis, the end product of the complex ergot alkaloid (EA) pathway inA. fumigatus. Deletion of eitherpesL(ΔpesL) orpes1(Δpes1) resulted in complete loss of fumigaclavine C biosynthesis, relatively increased production of fumitremorgins such as TR-2, fumitremorgin C and verruculogen, increased sensitivity to H2O2, and increased sensitivity to the antifungals, voriconazole, and amphotericin B. Deletion ofpesLresulted in severely reduced virulence in an invertebrate infection model (P< 0.001). These findings indicate that NRP synthesis plays an essential role in mediating the final prenylation step of the EA pathway, despite the apparent absence of NRP synthetases in the proposed EA biosynthetic cluster forA. fumigatus. Liquid chromatography/diode array detection/mass spectrometry analysis also revealed the presence of fumiquinazolines A to F in bothA. fumigatuswild-type and ΔpesLstrains. This observation suggests that alternative NRP synthetases can also function in fumiquinazoline biosynthesis, since PesL has been shown to mediate fumiquinazoline biosynthesisin vitro. Furthermore, we provide here the first direct link between EA biosynthesis and virulence, in agreement with the observed toxicity associated with EA exposure. Finally, we demonstrate a possible cluster cross-talk phenomenon, a theme which is beginning to emerge in the literature.

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Quorum-Sensing Regulation of Constitutive Plantaricin by Lactobacillus plantarum Strains under a Model System for Vegetables and Fruits

Applied and Environmental Microbiology ◽

10.1128/aem.03224-13 ◽

2013 ◽

Vol 80 (2) ◽

pp. 777-787 ◽

Cited By ~ 17

Author(s):

Carlo G. Rizzello ◽

Pasquale Filannino ◽

Raffaella Di Cagno ◽

Maria Calasso ◽

Marco Gobbetti

Keyword(s):

Quorum Sensing ◽

Lactobacillus Plantarum ◽

Antimicrobial Activities ◽

Model System ◽

Mass Spectrometry Analysis ◽

Carrot Juice ◽

Content Type ◽

Spectrometry Analysis ◽

Vegetables And Fruits

ABSTRACTThis study aimed at investigating the regulatory system of bacteriocin synthesis byLactobacillus plantarumstrains in vegetables and fruits in a model system. Sterile and neutralized cell-free supernatant (CFS) fromL. plantarumstrains grown in MRS broth showedin vitroantimicrobial activities toward various indicator strains. The highest activity was that ofL. plantarumC2. The antimicrobial activity was further assayed on vegetable and fruit agar plates (solid conditions) and in juices (liquid conditions). A regulatory mechanism of bacteriocin synthesis via quorum sensing was hypothesized. The synthesis of antimicrobial compounds seemed to be constitutive under solid conditions of growth on vegetable and fruit agar plates. In contrast, it depended on the size of the inoculum whenL. plantarumC2 was grown in carrot juice. Only the inoculum of ca. 9.0 log CFU ml−1produced detectable activity. The genesplnA,plnEF,plnG, andplnHwere found in allL. plantarumstrains. The genesplnJKandplnNwere detected in only three or four strains. Reverse-phase high-performance liquid chromatography purification and mass spectrometry analysis revealed the presence of a mixture of eight peptides in the most active fraction of the CFS fromL. plantarumC2. Active peptides were encrypted into bacteriocin precursors, such as plantaricins PlnJ/K and PlnH and PlnG, which are involved in the ABC transport system. A real-time PCR assay showed an increase in the expression ofplnJKandplnGduring growth ofL. plantarumC2 in carrot juice.

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Structure, Mechanism, and Inhibition of Aspergillus fumigatus Thioredoxin Reductase

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02281-18 ◽

2019 ◽

Vol 63 (3) ◽

Cited By ~ 3

Author(s):

Andrew C. Marshall ◽

Sarah E. Kidd ◽

Stephanie J. Lamont-Friedrich ◽

Georgia Arentz ◽

Peter Hoffmann ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Enzyme Inhibitor ◽

Redox Homeostasis ◽

Thioredoxin Reductase ◽

Antifungal Drugs ◽

Mass Spectrometry Analysis ◽

Content Type ◽

Spectrometry Analysis ◽

Future Design

ABSTRACT Aspergillus fumigatus infections are associated with high mortality rates and high treatment costs. Limited available antifungals and increasing antifungal resistance highlight an urgent need for new antifungals. Thioredoxin reductase (TrxR) is essential for maintaining redox homeostasis and presents as a promising target for novel antifungals. We show that ebselen [2-phenyl-1,2-benzoselenazol-3(2H)-one] is an inhibitor of A. fumigatus TrxR (Ki = 0.22 μM) and inhibits growth of Aspergillus spp., with in vitro MIC values of 16 to 64 µg/ml. Mass spectrometry analysis demonstrates that ebselen interacts covalently with a catalytic cysteine of TrxR, Cys148. We also present the X-ray crystal structure of A. fumigatus TrxR and use in silico modeling of the enzyme-inhibitor complex to outline key molecular interactions. This provides a scaffold for future design of potent and selective antifungal drugs that target TrxR, improving the potency of ebselen toward inhbition of A. fumigatus growth.

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Phytochemicals of Minthostachys diffusa Epling and Their Health-Promoting Bioactivities

Foods ◽

10.3390/foods9020144 ◽

2020 ◽

Vol 9 (2) ◽

pp. 144

Author(s):

Immacolata Faraone ◽

Daniela Russo ◽

Lucia Chiummiento ◽

Eloy Fernandez ◽

Alka Choudhary ◽

...

Keyword(s):

Ethyl Acetate ◽

Radical Scavenging ◽

Ethyl Acetate Fraction ◽

Mass Spectrometry Analysis ◽

Antioxidant Power ◽

Spectrometry Analysis ◽

In Silico Docking ◽

Aerial Parts ◽

Health Promoting

The genus Minthostachys belonging to the Lamiaceae family, and is an important South American mint genus used commonly in folk medicine as an aroma in cooking. The phytochemical-rich samples of the aerial parts of Minthostachys diffusa Epling. were tested for pharmacological and health-promoting bioactivities using in vitro chemical and enzymatic assays. A range of radical scavenging activities of the samples against biological radicals such as nitric oxide and superoxide anion and against synthetic 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals, the ferric reducing antioxidant power and the lipid peroxidation inhibition were determined and ranked using the ‘relative antioxidant capacity index’ (RACI). The ethyl acetate fraction showed the highest RACI of +1.12. Analysis of the various fractions’ inhibitory ability against enzymes involved in diabetes (α-amylase and α-glucosidase), and against enzymes associated with Parkinson’s or Alzheimer’s diseases (acetylcholinesterase and butyrylcholinesterase) also suggested that the ethyl acetate fraction was the most active. Liquid chromatography–tandem mass spectrometry analysis of the ethyl acetate fraction showed more than 30 polyphenolic compounds, including triterpenes. The inhibitory cholinesterase effects of the triterpenes identified from M. diffusa were further analysed by in silico docking of these compounds into 3D-structures of acetylcholinesterase and butyrylcholinesterase. This is the first study on pharmacological activities and phytochemical profiling of the aerial parts of M. diffusa, showing that this plant, normally used as food in South America, is also rich in health-promoting phytochemicals.

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A Comparative Study of the Antioxidative Effects of Helichrysum italicum and Helichrysum arenarium Infusions

Antioxidants ◽

10.3390/antiox10030380 ◽

2021 ◽

Vol 10 (3) ◽

pp. 380

Author(s):

Katja Kramberger ◽

Zala Jenko Pražnikar ◽

Alenka Baruca Arbeiter ◽

Ana Petelin ◽

Dunja Bandelj ◽

...

Keyword(s):

Oxidative Stress ◽

High Performance ◽

Radical Scavenging Activity ◽

Radical Scavenging ◽

Morphological Type ◽

Mass Spectrometry Analysis ◽

In Vitro Assays ◽

Spectrometry Analysis ◽

Stress Related Genes

Helichrysum arenarium (L.) Moench (abbrev. as HA) has a long tradition in European ethnomedicine and its inflorescences are approved as a herbal medicinal product. In the Mediterranean part of Europe, Helichrysum italicum (Roth) G. Don (abbrev. as HI) is more common. Since infusions from both plants are traditionally used, we aimed to compare their antioxidative potential using in vitro assays. Two morphologically distinct HI plants, HIa and HIb, were compared to a commercially available HA product. Genetic analysis using microsatellites confirmed a clear differentiation between HI and HA and suggested that HIb was a hybrid resulting from spontaneous hybridization from unknown HI subspecies. High-performance liquid chromatography–mass spectrometry analysis showed the highest amounts of hydroxycinnamic acids and total arzanol derivatives in HIa, whereas HIb was richest in monohydroxybenzoic acids, caffeic acids, and coumarins, and HA contained the highest amounts of flavonoids, especially flavanones. HIa exhibited the highest radical scavenging activity; it was more efficient in protecting different cell lines from induced oxidative stress and in inducing oxidative stress-related genes superoxide dismutase 1, catalase, and glutathione reductase 1. The antioxidative potential of HI was not only dependent on the morphological type of the plant but also on the harvest date, revealing important information for obtaining the best possible product. Considering the superior properties of HI compared to HA, the evaluation of HI as a medicinal plant could be recommended.

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Phytotoxicity of Essential Oils on Selected Weeds: Potential Hazard on Food Crops

Plants ◽

10.3390/plants7040079 ◽

2018 ◽

Vol 7 (4) ◽

pp. 79 ◽

Cited By ~ 12

Author(s):

María Ibáñez ◽

María Blázquez

Keyword(s):

Seed Germination ◽

Essential Oil ◽

Essential Oils ◽

Mass Spectrometry Analysis ◽

Gas Chromatography Mass Spectrometry ◽

Food Crops ◽

Potential Hazard ◽

Spectrometry Analysis

The chemical composition of winter savory, peppermint, and anise essential oils, and in vitro and in vivo phytotoxic activity against weeds (Portulaca oleracea, Lolium multiflorum, and Echinochloa crus-galli) and food crops (maize, rice, and tomato), have been studied. Sixty-four compounds accounting for between 97.67–99.66% of the total essential oils were identified by Gas Chromatography-Mass Spectrometry analysis. Winter savory with carvacrol (43.34%) and thymol (23.20%) as the main compounds produced a total inhibitory effect against the seed germination of tested weed. Menthol (48.23%), menthone (23.33%), and iso-menthone (16.33%) from peppermint only showed total seed germination inhibition on L. multiflorum, whereas no significant effects were observed with trans-anethole (99.46%) from anise at all concentrations (0.125–1 µL/mL). Low doses of peppermint essential oil could be used as a sustainable alternative to synthetic agrochemicals to control L. multiflorum. The results corroborate that in vivo assays with a commercial emulsifiable concentrate need higher doses of the essential oils to reproduce previous in vitro trials. The higher in vivo phytotoxicity of winter savory essential oil constitutes an eco-friendly and less pernicious alternative to weed control. It is possible to achieve a greater in vivo phytotoxicity if less active essential oil like peppermint is included with other active excipients.

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