scholarly journals Functional asymmetry and chemical reactivity of CsoR family persulfide sensors

2021 ◽  
Author(s):  
Joseph Fakhoury ◽  
Yifan Zhang ◽  
Katherine A Edmonds ◽  
Mauro Bringas ◽  
Justin Luebke ◽  
...  
Keyword(s):  
Methicillin Resistant Staphylococcus Aureus ◽  
Chemical Reactivity ◽  
Sequence Similarity ◽  
Crystallographic Structure ◽  
Gram Negative Bacteria ◽  
Identical Pair ◽  
Bacterial Response ◽  
Functionally Diverse ◽  
Repressor Activity ◽  
In Cells

CstR is a persulfide-sensing member of the functionally diverse copper-sensitive operon repressor (CsoR) superfamily that regulates the bacterial response to hydrogen sulfide (H2S) and more oxidized reactive sulfur species (RSS) in Gram-positive pathogens. A cysteine thiol pair on CstR reacts with RSS to form a mixture of interprotomer di-, tri- and tetrasulfide crosslinks, which drives transcriptional derepression of CstR-regulated genes. In some bacteria, notably methicillin-resistant Staphylococcus aureus (MRSA), CstR and CsoR, a Cu(I)-sensor, exhibit no regulatory crosstalk in cells, despite maintaining an identical pair of cysteines. We report a sequence similarity network (SSN) analysis of the entire CsoR superfamily, together with the first crystallographic structure of a CstR protein and mass spectrometry-based kinetic profiling experiments to obtain new insights into the molecular basis of RSS specificity in CstRs. The more N-terminal cysteine is the attacking Cys in CstR and is far more nucleophilic than in a CsoR. This cysteine, C30 in SpCstR, is separated from the resolving thiol, C59′, by an Asn55′ wedge. Chemical reactivity experiments reveal a striking asymmetry of reactivity, preserved in all CstRs and with all oxidants tested; however, the distribution of crosslinked products varies markedly among CstRs. Substitution of N55 with Ala in SpCstR significantly impacts the distribution of species, despite adopting the same structure as the parent repressor. We show that CstRs react with hydrogen peroxide, a finding that contrasts sharply with other structurally distinct persulfide sensors from Gram-negative bacteria. This suggests that other factors may enhance the specificity and repressor activity of CstRs in cells.

scholarly journals Folding Control in the Path of Type 5 Secretion

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 341
Author(s):  
Nathalie Dautin
Keyword(s):  
Protein Folding ◽  
Virulence Factors ◽  
Secretion System ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Final Destination ◽  
Cell Compartments ◽  
Recent Addition ◽  
Functionally Diverse

The type 5 secretion system (T5SS) is one of the more widespread secretion systems in Gram-negative bacteria. Proteins secreted by the T5SS are functionally diverse (toxins, adhesins, enzymes) and include numerous virulence factors. Mechanistically, the T5SS has long been considered the simplest of secretion systems, due to the paucity of proteins required for its functioning. Still, despite more than two decades of study, the exact process by which T5SS substrates attain their final destination and correct conformation is not totally deciphered. Moreover, the recent addition of new sub-families to the T5SS raises additional questions about this secretion mechanism. Central to the understanding of type 5 secretion is the question of protein folding, which needs to be carefully controlled in each of the bacterial cell compartments these proteins cross. Here, the biogenesis of proteins secreted by the Type 5 secretion system is discussed, with a focus on the various factors preventing or promoting protein folding during biogenesis.

Signaling and cytotoxic functions of 4-hydroxyalkenals

2010 ◽  
Vol 299 (6) ◽  
pp. E879-E886 ◽  
Author(s):  
Yael Riahi ◽  
Guy Cohen ◽  
Ofer Shamni ◽  
Shlomo Sasson
Keyword(s):  
Chemical Reactivity ◽  
Cellular Functions ◽  
Free Oxygen Radical ◽  
Lipid Molecule ◽  
Cell Functions ◽  
Peroxidation Product ◽  
Covalent Adducts ◽  
12 Lipoxygenase ◽  
Hydroperoxyeicosatetraenoic Acid ◽  
In Cells

The peroxidation of n-3 and n-6 polyunsaturated fatty acids (PUFAs) and of their hydroperoxy metabolites is a complex process. It is initiated by free oxygen radical-induced abstraction of a hydrogen atom from the lipid molecule followed by a series of nonenzymatic reactions that ultimately generate the reactive aldehyde species 4-hydroxyalkenals. The molecule 4-hydroxy- 2E-hexenal (4-HHE) is generated by peroxidation of n-3 PUFAs, such as linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. The aldehyde product 4-hydroxy-2 E-nonenal (4-HNE) is the peroxidation product of n-6 PUFAs, such as arachidonic and linoleic acids and their 15-lipoxygenase metabolites, namely 15-hydroperoxyeicosatetraenoic acid (15-HpETE) and 13-hydroperoxyoctadecadienoic acid (13-HpODE). Another reactive peroxidation product is 4-hydroxy-2 E,6 Z-dodecadienal (4-HDDE), which is derived from 12-hydroperoxyeicosatetraenoic acid (12-HpETE), the 12-lipoxygenase metabolite of arachidonic acid. Hydroxyalkenals, notably 4-HNE, have been implicated in various pathophysiological interactions due to their chemical reactivity and the formation of covalent adducts with macromolecules. The progressive accumulation of these adducts alters normal cell functions that can lead to cell death. The lipophilicity of these aldehydes positively correlates to their chemical reactivity. Nonetheless, at low and noncytotoxic concentrations, these molecules may function as signaling molecules in cells. This has been shown mostly for 4-HNE and to some extent for 4-HHE. The capacity of 4-HDDE to generate such “mixed signals” in cells has received less attention. This review addresses the origin and cellular functions of 4-hydroxyalkernals.

scholarly journals Antibacterial and Cytotoxic Activities of the Sesquiterpene Lactones Cnicin and Onopordopicrin

2011 ◽  
Vol 6 (2) ◽  
pp. 1934578X1100600 ◽  
Author(s):  
Sandra M. Bach ◽  
Mario A. Fortuna ◽  
Rodgoun Attarian ◽  
Juliana T. de Trimarco ◽  
César A. N. Catalán ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Sesquiterpene Lactones ◽  
Antibacterial Activities ◽  
Chloroform Extract ◽  
Cytotoxic Activities ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
High Cytotoxicity

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens.

scholarly journals Effect of the Surface Morphology of TiO2 Nanotubes on Photocatalytic Efficacy Using Electron-Transfer-Based Assays and Antimicrobial Tests

2020 ◽  
Vol 10 (15) ◽  
pp. 5243
Author(s):  
Frederick Lia ◽  
Clayton Farrugia ◽  
Maria Antonietta Buccheri ◽  
Giancarlo Rappazzo ◽  
Edwin Zammit ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Ethylene Glycol ◽  
Titanium Oxide ◽  
Tannic Acid ◽  
Chemical Reactivity ◽  
Supporting Electrolyte ◽  
Tube Length ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative

The application of titanium oxide nanotubes for the removal of contaminants from freshwater is a rapidly growing scientific interest, especially when it comes to water conservation strategies. In this study we employed four different titanium oxide nanotube surfaces, prepared by a two-electrode anodic oxidation. Two of the surfaces were synthesised in aqueous media, while the other two surfaces were synthesised in ethylene glycol. One of the arrays synthesised in the organic medium was impregnated with silver nanoparticles, while the remaining surfaces were not. The chemical reactivity of the various surfaces was assessed using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as free electron sensitive probe molecules, in parallel with tannic acid degradation and copper ion reducing capacity. The potential antimicrobial activity of the surfaces was assessed against a panel of microorganisms composed of yeast, fungi, Gram-positive and Gram-negative bacteria. Field emission scanning electron microscopy revealed that surfaces produced in the aqueous medium had a smaller tube length and a smaller tube diameter. It was noted that one of the materials using sodium sulfate as the supporting electrolyte had the most irregular nanostructure morphology with tubes growing to the side rather than vertically. The structural variation of the surfaces directly reflected both the chemical and biological activity, with the nanotubes formed in ethylene glycol showing the fastest rates in the stabilization of DPPH and ABTS radicals, the fastest tannic acid decomposition under various pH conditions and the fastest metal reducing activity. Furthermore, the surface containing silver and its bare counterpart showed the most effective antimicrobial activity, removing approximately 82% of Gram-negative bacteria, 50% of Gram-positive bacteria, 70% of yeast and 40% of fungi, with Gram-negative bacteria being the most susceptible to these surfaces.

scholarly journals Pseudomonas moraviensis sp. nov. and Pseudomonas vranovensis sp. nov., soil bacteria isolated on nitroaromatic compounds, and emended description of Pseudomonas asplenii

2006 ◽  
Vol 56 (11) ◽  
pp. 2657-2663 ◽  
Author(s):  
Ludmila Tvrzová ◽  
Peter Schumann ◽  
Cathrin Spröer ◽  
Ivo Sedláček ◽  
Zdena Páčová ◽  
...  
Keyword(s):  
Dna Hybridization ◽  
Type Strain ◽  
Additional Data ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Gram Negative Bacteria ◽  
Selective Enrichment ◽  
Gene Sequence Analysis ◽  
Emended Description ◽  
Pseudomonas Jessenii

Two strains of Gram-negative bacteria isolated from soil by selective enrichment with nitroaromatics were subjected to a polyphasic taxonomic study. On the basis of 16S rRNA gene sequence analysis, the two strains were found to belong to the genus Pseudomonas, within the Gammaproteobacteria. Strain 1B4T shared the highest sequence similarity with Pseudomonas koreensis DSM 16610T (99.5 %) and Pseudomonas jessenii CCM 4840T (99.3 %), and strain 2B2T with Pseudomonas asplenii DSM 17133T (98.9 %), Pseudomonas fuscovaginae DSM 7231T (98.9 %) and Pseudomonas putida DSM 291T (98.7 %). On the basis of phylogenetic analysis, DNA–DNA hybridization and phenotype, including chemotaxonomic characteristics, two novel species, Pseudomonas moraviensis sp. nov. with the type strain 1B4T (=CCM 7280T=DSM 16007T) and Pseudomonas vranovensis sp. nov. with the type strain 2B2T (=CCM 7279T=DSM 16006T), are proposed. The description of P. asplenii was emended on the basis of additional data obtained in this study.

Protein expression profiles in methicillin-resistant Staphylococcus aureus (MRSA) under effects of subminimal inhibitory concentrations of imipenem

2019 ◽  
Vol 366 (15) ◽  
Author(s):  
Jichun Wang ◽  
Junrui Wang ◽  
Yanyan Wang ◽  
Peng Sun ◽  
Xiaohui Zou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Cellular Proliferation ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Expression Profiles ◽  
Gram Negative Bacteria ◽  
Beta Lactam ◽  
Gram Negative ◽  
Methicillin Resistant

ABSTRACT Imipenem is a beta-lactam antibiotic mainly active against gram-negative bacterial pathogens and also could cause cell wall impairment in methicillin-resistant Staphylococcus aureus(MRSA). However, related antibacterial mechanisms of imipenem on MRSA and mixed infections of MRSA and gram-negative bacteria are relatively poorly revealed. This study was to identify proteins in the MRSA response to subminimal inhibitory concentrations (sub-MICs) of imipenem treatment. Our results showed that 240 and 58 different expression proteins (DEPs) in sub-MICs imipenem-treated S3 (a standard MRSA strain) and S23 (a clinical MRSA strain) strains were identified through the isobaric tag for relative and absolute quantitation method when compared with untreated S3 and S23 strains, respectively, which was further confirmed by multiple reactions monitoring. Our result also demonstrated that expressions of multiple DEPs involved in cellular proliferation, metabolism and virulence were significantly changed in S3 and S23 strains, which was proved by gene ontology annotations and qPCR analysis. Further, transmission electron microscopy and scanning electron microscopy analysis showed cell wall deficiency, cell lysis and abnormal nuclear mitosis on S23 strain. Our study provides important information for understanding the antibacterial mechanisms of imipenem on MRSA and for better usage of imipenem on patients co-infected with MRSA and other multidrug-resistant gram-negative bacteria.

scholarly journals Pantoeasp. Isolated from Tropical Fresh Water ExhibitingN-Acyl Homoserine Lactone Production

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Wen-Si Tan ◽  
Nina Yusrina Muhamad Yunos ◽  
Pui-Wan Tan ◽  
Nur Izzati Mohamad ◽  
Tan-Guan-Sheng Adrian ◽  
...  
Keyword(s):  
Gene Sequence ◽  
Sequence Similarity ◽  
Environmental Water ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Gram Negative Bacteria ◽  
Water Sampling ◽  
16S Rdna Gene ◽  
Preliminary Screening ◽  
Pantoea Stewartii

N-Acyl homoserine lactone (AHL) serves as signaling molecule for quorum sensing (QS) in Gram-negative bacteria to regulate various physiological activities including pathogenicity. With the aim of isolating freshwater-borne bacteria that can cause outbreak of disease in plants and portrayed QS properties, environmental water sampling was conducted. Here we report the preliminary screening of AHL production usingChromobacterium violaceumCV026 andEscherichia coli[pSB401] as AHL biosensors. The 16S rDNA gene sequence of isolate M009 showed the highest sequence similarity toPantoea stewartiiS9-116, which is a plant pathogen. The isolatedPantoeasp. was confirmed to produceN-3-oxohexanoyl-L-HSL (3-oxo-C6-HSL) through analysis of high resolution mass tandem mass spectrometry.

scholarly journals Adult Native Joint Septic Arthritis: A Nine-Year Retrospective Analysis in a Portuguese University Hospital

2021 ◽  
Vol 34 (13) ◽  
Author(s):  
Ana Cipriano ◽  
Fábio Videira Santos ◽  
Rita Dias ◽  
André Carvalho ◽  
Ernestina Reis ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Septic Arthritis ◽  
Retrospective Analysis ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Empirical Treatment ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Methicillin Resistant ◽  
Wide Range ◽  
Amoxicillin Clavulanate

Introduction: Septic arthritis of a native joint represents a medical emergency. Drainage and effective antibiotic treatment are critical to avoid joint destruction and long-term impairment. The aim of this study was to evaluate epidemiological and clinical characteristics of patients with the diagnosis of septic arthritis to help establish local guidelines for empirical antibiotic treatment.Material and Methods: Retrospective analysis of adult patients admitted at Centro Hospitalar Universitário do Porto from 2009 to 2017 with suspected native joint septic arthritis. Relevant demographics, microbiology findings and respective antibiotic susceptibilities were analysed.Results: Ninety-seven patients, predominantly males (59.8%) with a median age of 61 years old were included. The most commonly reported comorbidity associated with septic arthritis was diabetes mellitus (20.6%). The knee was the most commonly affected joint (71.1%). Arthrocentesis was performed in all patients, but only 50.5% had positive microbial growth in the synovial fluid. Staphylococcus aureus was the most frequently identified microorganism, 86% of which were methicillin susceptible. Gram-negative bacteria were the causative agent in 15% of cases. A wide range of empirical antibiotic regimens were prescribed with a combination of vancomycin/carbapenem being the most common (30.9%). Analysis of antibiotic susceptibility profiles revealed that amoxicillin/clavulanate would have been appropriate as the initial regimen in 89% of cases.Discussion: The main causative pathogen was Staphylococcus aureus, with methicillin resistant Staphylococcus aureus remaining rare. The proportion of Gram-negative bacteria implies that these agents should be covered by empirical treatment, although no case of Pseudomonas infection has been identified. Therefore, antipseudomonal coverage is not necessary in empirical regimens.Conclusion: Routine coverage of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa is not warranted but must be considered when specific risk factors are found. Amoxicillin/clavulanate can provide adequate antibiotic coverage as an empirical treatment for adult native joint septic arthritis. Its use may allow a reduction in use of broader spectrum antibiotics.

A multisubunit membrane-bound [NiFe] hydrogenase and an NADH-dependent Fe-only hydrogenase in the fermenting bacterium Thermoanaerobacter tengcongensis

Microbiology ◽  
2004 ◽  
Vol 150 (7) ◽  
pp. 2451-2463 ◽  
Author(s):  
Basem Soboh ◽  
Dietmar Linder ◽  
Reiner Hedderich
Keyword(s):  
Sequence Similarity ◽  
Kinetic Studies ◽  
Methanosarcina Barkeri ◽  
Hydrogenase Activity ◽  
Iron Sulfur Clusters ◽  
High Hydrogen ◽  
Thermoanaerobacter Tengcongensis ◽  
Membrane Bound ◽  
Energy Converting ◽  
In Cells

Thermoanaerobacter tengcongensis is a thermophilic Gram-positive bacterium able to dispose of the reducing equivalents generated during the fermentation of glucose to acetate and CO2 by reducing H+ to H2. A unique combination of hydrogenases, a ferredoxin-dependent [NiFe] hydrogenase and an NADH-dependent Fe-only hydrogenase, were found to be responsible for H2 formation in this organism. Both enzymes were purified and characterized. The tightly membrane-bound [NiFe] hydrogenase belongs to a small group of complex-I-related [NiFe] hydrogenases and has highest sequence similarity to energy-converting [NiFe] hydrogenase (Ech) from Methanosarcina barkeri. A ferredoxin isolated from Ta. tengcongensis was identified as the physiological substrate of this enzyme. The heterotetrameric Fe-only hydrogenase was isolated from the soluble fraction. It contained FMN and multiple iron–sulfur clusters, and exhibited a typical H-cluster EPR signal after autooxidation. Sequence analysis predicted and kinetic studies confirmed that the enzyme is an NAD(H)-dependent Fe-only hydrogenase. When H2 was allowed to accumulate in the culture, the fermentation was partially shifted to ethanol production. In cells grown at high hydrogen partial pressure [p(H2)] the NADH-dependent hydrogenase activity was fourfold lower than in cells grown at low p(H2), whereas aldehyde dehydrogenase and alcohol dehydrogenase activities were higher in cells grown at elevated p(H2). These results indicate a regulation in response to the p(H2).

Sign in / Sign up

Export Citation Format

Share Document