Extensive Comparative Genomic Analysis of Enterococcus faecalis and Enterococcus faecium Reveals a Direct Association between the Absence of CRISPR-Cas Systems, the Presence of Anti-Endonuclease (ardA) and the Acquisition of Vancomycin Resistance in E. faecium

Here, we performed a comparative genomic analysis of all available genomes of E. faecalis (n = 1591) and E. faecium (n = 1981) and investigated the association between the presence or absence of CRISPR-Cas systems, endonuclease/anti-endonuclease systems and the acquisition of antimicrobial resistance, especially vancomycin resistance genes. Most of the analysed Enterococci were isolated from humans and less than 14% of them were from foods and animals. We analysed and detected CRISPR-Cas systems in 75.36% of E. faecalis genomes and only 4.89% of E. faecium genomes with a significant difference (p-value < 10-5). We found a negative correlation between the number of CRISPR-Cas systems and genome size (r = -0.397, p-value < 10-5) and a positive correlation between the genome %GC content and the number of CRISPR-Cas systems (r = 0.215, p-value < 10-5).
Our findings showed that the presence of the anti-endonuclease ardA gene may explain the decrease in the number of CRISPR-Cas systems in E. faecium, known to deactivate the endonucleases’ protective activities and enable the E. faecium genome to be versatile in acquiring mobile genetic elements, including carriers of antimicrobial resistance genes, especially vanB. Most importantly, we observed that there was a direct association between the absence of CRISPR-Cas, the presence of the anti-CRISPR ardA gene and the acquisition of vancomycin resistance genes.

Unraveling the anti-influenza effect of flavonoids: Experimental validation of luteolin and its congeners as potent influenza endonuclease inhibitors

The biological effects of flavonoids on mammal cells are diverse, ranging from scavenging free radicals and anti-cancer activity to anti-influenza activity. Despite appreciable effort to understand the anti-influenza activity of flavonoids, there is no clear consensus about their precise mode-of-action at a cellular level. Here, we report the development and validation of a screening assay based on AlphaScreen technology and illustrate its application for determination of the inhibitory potency of a large set of polyols against PA N-terminal domain (PA-Nter) of influenza RNA-dependent RNA polymerase featuring endonuclease activity.
The most potent inhibitors we identified were luteolin with an IC50 of 72 ± 2 nM and its 8-C-glucoside orientin with an IC50 of 43 ± 2 nM. Submicromolar inhibitors were also evaluated by an in vitro endonuclease activity assay using single-stranded DNA, and the results were in full agreement with data from the competitive AlphaScreen assay. Using X-ray crystallography, we analyzed structures of the PA-Nter in complex with luteolin at 2.0 Å resolution and quambalarine B at 2.5 Å resolution, which clearly revealed the binding pose of these polyols coordinated to two manganese ions in the endonuclease active site. Using two distinct assays along with the structural work, we have presumably identified and characterized the molecular mode-of-action of flavonoids in influenza-infected cells.

Non-chelating p-phenylidene-linked bis-imidazoline analogs of known influenza virus endonuclease inhibitors: Synthesis and anti-influenza activity.

A novel chemotype topologically similar to known influenza virus PA endonuclease inhibitors has been designed. It was aimed to reproduce the extended topology of the known metal-chelating ligands with a p-phenylidene-linked bis-imidazoline scaffold. It was envisioned that aromatic groups introduced to this scaffolds via metal-catalyzed N-arylation (Buchwald-Hartwig or Chan-Evans-Lam) would contribute to lipophilic binding to the target and one of the imidazoline nitrogen atoms would ensure non-chelating coordination to the prosthetic divalent metal ion.
The compounds displayed appreciable anti-influenza activity in vitro and substantial concentration window from the general cytotoxicity range. Docking analysis of low-energy poses of the most active compound (as well as their comparison to the binding of an inactive compound) revealed that these compounds reproduced similar binding components to a known PA endonuclease inhibitor and displayed similar binding pose and desired monodentate metal coordination, as was initially envisioned. These findings warrant further investigation of the mechanism of action of the newly discovered series.

The anti-inflammatory role of extranuclear apurinic/apyrimidinic endonuclease 1/redox effector factor-1 in reactive astrocytes.

  • Apurinic/apyrimidinic endonuclease 1 (APE1), a ubiquitous multipurpose protein, is also known as redox effector factor-1 (Ref-1). It is involved in DNA repair and redox signaling and, in turn, oxidative stress-induced neurodegeneration. Although previous studies have demonstrated that APE1/Ref-1 functions as a negative regulator of inflammatory response via several mechanisms in neuronal cells, little is known about the roles of APE1/Ref-1 in glial cells. In this study, we found that cytoplasmic APE1/Ref-1 expression was upregulated in reactive astrocytes of the kainic acid- or lipopolysaccharide (LPS)-injected hippocampus.
  • Analysis of the inflammatory response induced by extranuclear APE1/Ref-1 (ΔNLS-Ref-1) in cultured primary astrocytes revealed that it markedly suppressed inducible nitric oxide synthase (iNOS) expression and tumor necrosis factor-α (TNF-α) secretion induced by LPS to a similar extent as did wild type APE1/Ref-1 (WT-Ref-1), supporting the concept an anti-inflammatory role of extranuclear APE1/Ref-1 in astrocytes. Additionally, overexpression of WT- and ΔNLS-Ref-1 suppressed the transcriptional activity of nuclear factor-κB (NF-κB), although it effectively enhanced activator protein 1 (AP-1) activity.
  • The blunting effect of APE1/Ref-1 on LPS-induced NF-κB activation was not mediated by IκB kinase (IKK) activity. Instead, APE1/Ref-1 inhibited p300-mediated acetylation of p65 by suppressing intracellular reactive oxygen species (ROS) levels following LPS treatment. Taken together, our results showed that altered expression and/or subcellular distribution of APE1/Ref-1 in activated astrocytes regulated the neuroinflammatory response to excitotoxin and endotoxin insults used in model of neurodegenerative brain diseases.

Rabbit Polyclonal antibody Anti-CRBN

Anti-CRBN ImmunoStep 50 µg 349 EUR

Endonuclease

GZ9793-25000U Glentham Life Sciences 25000 U 788 EUR

Endonuclease

GZ9793-5000U Glentham Life Sciences 5000 U 269 EUR

Polyclonal Goat anti-GST α-form

GST-ANTI-1 Detroit R&D 50 uL 280 EUR

Polyclonal Goat anti-GST μ-form

GST-ANTI-2 Detroit R&D 50 uL 280 EUR

Polyclonal Goat anti-GST p-form

GST-ANTI-3 Detroit R&D 50 uL 280 EUR

Rabbit Anti Endonuclease G Polyclonal Antibody

CPBT-66406RE Creative Diagnostics 0.1 mg 580 EUR

Endonuclease Antigenic Site

5-01097 CHI Scientific 4 x 1mg Ask for price

T7 Endonuclease I

EN303-01 Vazyme 250 U 143 EUR

T7 Endonuclease I

EN303-02 Vazyme 1250 U 274 EUR

T7 Endonuclease I

M1221-100 Biovision 349 EUR

Endonuclease G (ENDOG) Antibody

20-abx125812 Abbexa
  • 411.00 EUR
  • 592.00 EUR
  • 182.00 EUR
  • 314.00 EUR
  • 100 ul
  • 200 ul
  • 20 ul
  • 50 ul

Endonuclease G (ENDOG) Antibody

20-abx318051 Abbexa
  • 411.00 EUR
  • 1845.00 EUR
  • 599.00 EUR
  • 182.00 EUR
  • 300.00 EUR
  • 100 ug
  • 1 mg
  • 200 ug
  • 20 ug
  • 50 ug

Endonuclease IV, 2u/ul

BEN0591 Bio Basic 100U 121.78 EUR

Serratia Marcescens Endonuclease (Recombinant)

20-abx073081 Abbexa
  • 230.00 EUR
  • 1609.00 EUR
  • 328.00 EUR
  • 1 µg
  • 50 ug
  • 5 ug

E.Coli Endonuclease-III (Recombinant)

20-abx073709 Abbexa
  • 328.00 EUR
  • 6397.00 EUR
  • 230.00 EUR
  • 10 ug
  • 1 mg
  • 2 µg

Endonuclease G (ENDOG) Antibody

20-abx009296 Abbexa
  • 300.00 EUR
  • 439.00 EUR
  • 189.00 EUR
  • 100 ul
  • 200 ul
  • 30 ul

Endonuclease G (ENDOG) Antibody

abx032875-400ul Abbexa 400 ul 523 EUR

Endonuclease G (ENDOG) Antibody

abx032875-80l Abbexa 80 µl 286 EUR

Recombinant E.Coli Endonuclease-III

7-03244 CHI Scientific 2µg Ask for price

Recombinant E.Coli Endonuclease-III

7-03245 CHI Scientific 10µg Ask for price

Recombinant E.Coli Endonuclease-III

7-03246 CHI Scientific 1mg Ask for price

A Novel Endonuclease Inhibitor Exhibits Broad-Spectrum Anti-Influenza Virus Activity In Vitro.

Antiviral drugs are important in preventing and controlling influenza, particularly when vaccines are ineffective or unavailable. A single class of antiviral drugs, the neuraminidase inhibitors (NAIs), is recommended for treating influenza. The limited therapeutic options and the potential risk of antiviral resistance are driving the search for additional small-molecule inhibitors that act on influenza virus proteins.
The acid polymerase (PA) of influenza viruses is a promising target for new antivirals because of its essential role in initiating virus transcription. Here, we characterized a novel compound, RO-7, identified as a putative PA endonuclease inhibitor. RO-7 was effective when added before the cessation of genome replication, reduced polymerase activity in cell-free systems, and decreased relative amounts of viral mRNA and genomic RNA during influenza virus infection. RO-7 specifically inhibited the ability of the PA endonuclease domain to cleave a nucleic acid substrate. RO-7 also inhibited influenza A viruses (seasonal and 2009 pandemic H1N1 and seasonal H3N2) and B viruses (Yamagata and Victoria lineages), zoonotic viruses (H5N1, H7N9, and H9N2), and NAI-resistant variants in plaque reduction, yield reduction, and cell viability assays in Madin-Darby canine kidney (MDCK) cells with nanomolar to submicromolar 50% effective concentrations (EC50s), low toxicity, and favorable selective indices. RO-7 also inhibited influenza virus replication in primary normal human bronchial epithelial cells. Overall, RO-7 exhibits broad-spectrum activity against influenza A and B viruses in multiple in vitro assays, supporting its further characterization and development as a potential antiviral agent for treating influenza.

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