High-Throughput Screening for RecA Inhibitors Using a Transcreener Adenosine 5′-<i>O</i>-Diphosphate Assay

Peterson, Eliza J.R.; Janzen, William P.; Kireev, Dmitri; Singleton, Scott F.

doi:10.1089/adt.2011.0409

Cited by 36 publications

(37 citation statements)

References 45 publications

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“…Some metabolites in combination with aminoglycosides are able to eradicate persister cells (17). RecA inhibitors and vitamin E potentiate the activity of certain antibiotics (18,19). Thus, the use of antibiotic adjuvants is not a new idea, but so far, only the combination of ␤-lactamase inhibitors and ␤-lactam antibiotics has made it into the clinic.…”

Section: Discussionmentioning

confidence: 99%

Novel Quorum-Quenching Agents Promote Methicillin-Resistant Staphylococcus aureus (MRSA) Wound Healing and Sensitize MRSA to β-Lactam Antibiotics

Kuo

Hoch

et al. 2015

Antimicrob Agents Chemother

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The dwindling repertoire of antibiotics to treat methicillin-resistant Staphylococcus aureus (MRSA) calls for novel treatment options. Quorum-quenching agents offer an alternative or an adjuvant to antibiotic therapy. Three biaryl hydroxyketone compounds discovered previously (F1, F12, and F19; G. Yu, D. Kuo, M. Shoham, and R. Viswanathan, ACS Comb Sci 16:85-91, 2014) were tested for efficacy in MRSA-infected animal models. Topical therapy of compounds F1 and F12 in a MRSA murine wound infection model promotes wound healing compared to the untreated control. Compounds F1, F12, and F19 afford significant survival benefits in a MRSA insect larva model. Combination therapy of these quorum-quenching agents with cephalothin or nafcillin, antibiotics to which MRSA is resistant in monotherapy, revealed additional survival benefits. The quorum-quenching agents sensitize MRSA to the antibiotic by a synergistic mode of action that also is observed in vitro. An adjuvant of 1 g/ml F1, F12, or F19 reduces the MIC of nafcillin and cephalothin about 50-fold to values comparable to those for vancomycin, the antibiotic often prescribed for MRSA infections. These findings suggest that it is possible to resurrect obsolete antibiotic therapies in combination with these novel quorum-quenching agents. Methicillin-resistant Staphylococcus aureus (MRSA) is a widespread bacterial pathogen, causing various infections, ranging from skin and soft tissue infections to serious invasive infections, such as pneumonia, endocarditis, bacteremia, and sepsis (1, 2). Rising antibiotic resistance and diminishing investment by the pharmaceutical industry in the development of new antibiotics have created an urgent need for novel anti-MRSA agents (3). Quorum-quenching agents provide an alternative and an adjuvant to conventional antibiotic therapy (4, 5). The mechanism of action of quorum-quenching agents is fundamentally different from that for antibiotics. Quorum-quenching agents are neither bactericidal nor bacteriostatic. They inhibit the production of disease-causing toxins by the pathogen, thereby disarming the pathogen of its capacity to inactivate host defense factors. An intact host immune system has a better chance to clear a bacterial infection. A quorum-quenching agent tips the balance of bacterial virulence factors and host defense factors in favor of the host.Virulence factor production in Staphylococcus aureus is regulated by a quorum-sensing mechanism predominantly under the control of the agr operon (6, 7). In previous work, we have identified small-molecule biaryl hydroxyketone compounds that target the response regulator AgrA and inhibit its interaction with promoter P3, curtailing the production of toxins and virulence factors (8). In a follow-up study, a combinatorial library of 148 compounds was synthesized based on the most efficacious hit compound (9). A member of this biaryl hydroxyketone library, named F12, was the most efficacious of the synthesized compounds, demonstrating 98% in vitro MRSA rabbit erythrocyte hemolysis inhi...

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Section: Discussionmentioning

confidence: 99%

Novel Quorum-Quenching Agents Promote Methicillin-Resistant Staphylococcus aureus (MRSA) Wound Healing and Sensitize MRSA to β-Lactam Antibiotics

Kuo

Hoch

et al. 2015

Antimicrob Agents Chemother

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“…The 4,727 compound kinase-directed library was prepared and provided by the UNC Center for Integrative Chemical Biology and Drug Discovery (CICBDD) 49, 50 (22, 40) (23, 41) (23, 41). This compound set was selected from >100,000 compounds reviewed from Life Chemicals, ChemDiv, Asinex and Enamine kinase-focused libraries based on their similarity to known kinase inhibitors as well as to compounds having a hinge-binding motif (e.g.…”

Section: Methodsmentioning

confidence: 99%

Identification of Small Molecule Inhibitors That Block the Toxoplasma gondii Rhoptry Kinase ROP18

Simpson

Jones²,

Hull-Ryde

et al. 2016

ACS Infect. Dis.

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The protozoan parasite Toxoplasma gondii secretes a family of serine-threonine protein kinases into its host cell in order to disrupt signaling and alter immune responses. One prominent secretory effector is the rhoptry protein 18 (ROP18), a serine-threonine kinase that phosphorylates immunity related GTPases (IRGs) and hence blocks interferon gamma-mediated responses in rodent cells. Previous genetic studies show that ROP18 is a major virulence component of T. gondii strains from North and South America. Here, we implemented a high throughput screen to identify small molecule inhibitors of ROP18 in vitro and subsequently validated their specificity within infected cells. Although ROP18 was not susceptible to many kinase-directed inhibitors that affect mammalian kinases, the screen identified several sub micromolar inhibitors that belong to three chemical scaffolds: oxindoles, 6-azaquinazolines, and pyrazolopyridines. Treatment of interferon gamma-activated cells with one of these inhibitors enhanced immunity related GTPase recruitment to wild type parasites, recapitulating the defect of Δrop18 mutant parasites, consistent with targeting ROP18 within infected cells. These compounds provide useful starting points for chemical biology experiments or as leads for therapeutic interventions designed to reduce parasite virulence.

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“…Moreover, the Kinase Focus Set has yielded selective and potent inhibitors against another nucleic acid-processing enzyme. 35 …”

Section: Resultsmentioning

confidence: 99%

Inhibitors of Streptococcus pneumoniae Surface Endonuclease EndA Discovered by High-Throughput Screening Using a PicoGreen Fluorescence Assay

et al. 2013

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The human commensal pathogen, Streptococcus pneumoniae, expresses a number of virulence factors that promote serious pneumococcal diseases, resulting in significant morbidity and mortality worldwide. These virulence factors may give S. pneumoniae the capacity to escape immune defenses, resist antimicrobial agents, or a combination of both. Virulence factors also present possible points of therapeutic intervention. The activities of the surface endonuclease, EndA, allow S. pneumoniae to establish invasive pneumococcal infection. EndA’s role in DNA uptake during transformation contributes to gene transfer and genetic diversitifcation. Moreover, EndA’s nuclease activity degrades the DNA backbone of neutrophil extracellular traps (NETs), allowing pneumococcus to escape host immune responses. Given its potential impact on pneumococcal pathogenicity, EndA is an attractive target for novel antimicrobial therapy. Herein, we describe the development of a high-throughput screening assay for the discovery of nuclease inhibitors. Nuclease-mediated digestion of double-stranded DNA was assessed using fluorescence intensity changes of the DNA dye ligand, PicoGreen. Under optimized conditions, the assay provided robust and reproducible activity data (Z'=0.87) and was used to screen 4727 small molecules against an imidazole-rescued variant of EndA. In total, 10 small molecules were confirmed as novel EndA inhibitors that may have utility as research tools for understanding pneumococcal pathogenesis, and ultimately drug discovery.

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High-Throughput Screening for RecA Inhibitors Using a Transcreener Adenosine 5′-O-Diphosphate Assay

Cited by 36 publications

References 45 publications

Novel Quorum-Quenching Agents Promote Methicillin-Resistant Staphylococcus aureus (MRSA) Wound Healing and Sensitize MRSA to β-Lactam Antibiotics

Novel Quorum-Quenching Agents Promote Methicillin-Resistant Staphylococcus aureus (MRSA) Wound Healing and Sensitize MRSA to β-Lactam Antibiotics

Identification of Small Molecule Inhibitors That Block the Toxoplasma gondii Rhoptry Kinase ROP18

Inhibitors of Streptococcus pneumoniae Surface Endonuclease EndA Discovered by High-Throughput Screening Using a PicoGreen Fluorescence Assay

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