Recombinant Microorganisms as Tools for High Throughput Screening for Nonantibiotic Compounds

1997 ◽  
Vol 2 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Ronald D. Klein ◽  
Timothy G. Geary
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Heterologous Protein ◽  
Recombinant Dna ◽  
Biologically Active ◽  
Heterologous Proteins ◽  
Recombinant Dna Technology ◽  
Antibiotic Development ◽  
Recombinant Microorganisms

Microorganisms were among the first tools used for the discovery of biologically active compounds. Their utility reached a zenith during the era of antibiotic development in the 1950s and 1960s, then declined. Subsequently, a substantial role for microorganisms in the pharmaceutical industry developed with the realization that microbial fermentations were intriguing sources of nonantibiotic natural products. From recombinant DNA technology emerged another important role for microorganisms in pharmaceutical research: the expression of heterologous proteins for therapeutic products or for in vitro high throughput screens (HTSs). Recent developments in cloning, genetics, and expression systems have opened up new applications for recombinant microorganisms in screening for nonantibiotic compounds in HTSs. These screens employ microorganisms that depend upon the function of a heterologous protein for survival under defined nutritional conditions. Compounds that specifically target the heterologous protein can be identified by measuring viability of the microorganism under different nutrient selection. Advantages of this approach include a built-in selection for target selectivity, an easily measured end point that can be used for a multitude of different targets, and compatibility with automation required for HTSs. Mechanism-based HTSs using recombinant microorganisms can also address drug targets that are not readily approachable in other HTS formats, including certain enzymes; ion channels and transporters; and protein::protein, protein::DNA, and protein::RNA interactions.

scholarly journals Development of a Miniaturized 384-Well High Throughput Screen for the Detection of Substrates of Cytochrome P450 2D6 and 3A4 Metabolism

2001 ◽  
Vol 6 (2) ◽  
pp. 91-99 ◽  
Author(s):  
Ilona Kariv ◽  
Mark P. Fereshteh ◽  
Kevin R. Oldenburg
Keyword(s):  
Drug Metabolism ◽  
High Throughput ◽  
High Throughput Screening ◽  
Biologically Active ◽  
In Vitro Assays ◽  
Main Concern ◽  
Assay Sensitivity ◽  
Cyp Enzymes ◽  
Assay Optimization

The identification of a large number of biologically active chemical entities during high throughput screening (HTS) necessitates the incorporation of new strategies to identify compounds with druglike properties early during the lead prioritization and development process. One of the major steps in lead prioritization is the assessment of drug metabolism mediated by the cytochrome P450 (CYP) enzymes to evaluate the potential drug-drug interactions. CYP2D6 and CYP3A4 comprise the main human CYP enzymes involved in drug metabolism. The recent availability of specific CYP cDNA expression systems and the development of specific fluorescent probes have accelerated the ability to develop robust in vitro assays in HTS format. The aim of this study was to optimize conditions for the CYP2D6 and CYP3A4 HTS assays and subsequently adapt those assays to a miniaturized 384-well format. Assay conversion to a miniaturized format presents certain difficulties, such as robustness of the signal and of compound delivery. Thus the assay optimization involved the comparison of different substrates to identify those most suitable for use in a miniaturized format. Because of current technical limitations in liquid dispensing of nanoliter volumes, assay sensitivity to organic solvents also provides a main concern during assay miniaturization. Therefore, compound activity from redissolved dry films and from DMSO stocks directly delivered into assay buffer was compared. The data indicate that compound activity was comparable in both formats. The data support the conclusion that CYP2D6 and CYP3A4 in vitro metabolism assays can be successfully performed in 384-well plate format and the substrate potencies, as evaluated by the IC50 values, determined.

scholarly journals A high-throughput screening method for evolving a demethylase enzyme with improved and new functionalities

2020 ◽  
Author(s):  
Yuru Wang ◽  
Christopher D Katanski ◽  
Christopher Watkins ◽  
Jessica N Pan ◽  
Qing Dai ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Screening Method ◽  
Targeted Mutagenesis ◽  
Rna Repair ◽  
Dna And Rna ◽  
Modified Dna ◽  
Dna Substrates ◽  
Trna Sequencing

Abstract AlkB is a DNA/RNA repair enzyme that removes base alkylations such as N1-methyladenosine (m1A) or N3-methylcytosine (m3C) from DNA and RNA. The AlkB enzyme has been used as a critical tool to facilitate tRNA sequencing and identification of mRNA modifications. As a tool, AlkB mutants with better reactivity and new functionalities are highly desired; however, previous identification of such AlkB mutants was based on the classical approach of targeted mutagenesis. Here, we introduce a high-throughput screening method to evaluate libraries of AlkB variants for demethylation activity on RNA and DNA substrates. This method is based on a fluorogenic RNA aptamer with an internal modified RNA/DNA residue which can block reverse transcription or introduce mutations leading to loss of fluorescence inherent in the cDNA product. Demethylation by an AlkB variant eliminates the blockage or mutation thereby restores the fluorescence signals. We applied our screening method to sites D135 and R210 in the Escherichia coli AlkB protein and identified a variant with improved activity beyond a previously known hyperactive mutant toward N1-methylguanosine (m1G) in RNA. We also applied our method to O6-methylguanosine (O6mG) modified DNA substrates and identified candidate AlkB variants with demethylating activity. Our study provides a high-throughput screening method for in vitro evolution of any demethylase enzyme.

scholarly journals Investigating Molecular Mechanisms of Immunotoxicity and the Utility of ToxCast for Immunotoxicity Screening of Chemicals Added to Food

2021 ◽  
Vol 18 (7) ◽  
pp. 3332
Author(s):  
Olga V. Naidenko ◽  
David Q. Andrews ◽  
Alexis M. Temkin ◽  
Tasha Stoiber ◽  
Uloma Igara Uche ◽  
...  
Keyword(s):  
Immune System ◽  
High Throughput ◽  
Environmental Protection Agency ◽  
High Throughput Screening ◽  
Molecular Mechanisms ◽  
Specific Activity ◽  
Laboratory Animals ◽  
In Vitro Assays ◽  
Toxicological Studies

The development of high-throughput screening methodologies may decrease the need for laboratory animals for toxicity testing. Here, we investigate the potential of assessing immunotoxicity with high-throughput screening data from the U.S. Environmental Protection Agency ToxCast program. As case studies, we analyzed the most common chemicals added to food as well as per- and polyfluoroalkyl substances (PFAS) shown to migrate to food from packaging materials or processing equipment. The antioxidant preservative tert-butylhydroquinone (TBHQ) showed activity both in ToxCast assays and in classical immunological assays, suggesting that it may affect the immune response in people. From the PFAS group, we identified eight substances that can migrate from food contact materials and have ToxCast data. In epidemiological and toxicological studies, PFAS suppress the immune system and decrease the response to vaccination. However, most PFAS show weak or no activity in immune-related ToxCast assays. This lack of concordance between toxicological and high-throughput data for common PFAS indicates the current limitations of in vitro screening for analyzing immunotoxicity. High-throughput in vitro assays show promise for providing mechanistic data relevant for immune risk assessment. In contrast, the lack of immune-specific activity in the existing high-throughput assays cannot validate the safety of a chemical for the immune system.

scholarly journals High-throughput screening and rational design of biofunctionalized surfaces with optimized biocompatibility and antimicrobial activity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhou Fang ◽  
Junjian Chen ◽  
Ye Zhu ◽  
Guansong Hu ◽  
Haoqian Xin ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
High Throughput ◽  
High Throughput Screening ◽  
Rational Design ◽  
Click Reaction ◽  
Reaction Times ◽  
Great Promise ◽  
Biomaterial Surfaces

AbstractPeptides are widely used for surface modification to develop improved implants, such as cell adhesion RGD peptide and antimicrobial peptide (AMP). However, it is a daunting challenge to identify an optimized condition with the two peptides showing their intended activities and the parameters for reaching such a condition. Herein, we develop a high-throughput strategy, preparing titanium (Ti) surfaces with a gradient in peptide density by click reaction as a platform, to screen the positions with desired functions. Such positions are corresponding to optimized molecular parameters (peptide densities/ratios) and associated preparation parameters (reaction times/reactant concentrations). These parameters are then extracted to prepare nongradient mono- and dual-peptide functionalized Ti surfaces with desired biocompatibility or/and antimicrobial activity in vitro and in vivo. We also demonstrate this strategy could be extended to other materials. Here, we show that the high-throughput versatile strategy holds great promise for rational design and preparation of functional biomaterial surfaces.

scholarly journals High content and high throughput screening to assess the angiogenic and neurogenic actions of mesenchymal stem cells in vitro

2015 ◽  
Vol 333 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Jennifer J. Bara ◽  
Sarah Turner ◽  
Sally Roberts ◽  
Gareth Griffiths ◽  
Rod Benson ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
High Throughput ◽  
High Throughput Screening

Kinetic Assay for High-Throughput Screening of In Vitro Transthyretin Amyloid Fibrillogenesis Inhibitors

2005 ◽  
Vol 7 (2) ◽  
pp. 246-252 ◽  
Author(s):  
Ignacio Dolado ◽  
Joan Nieto ◽  
Maria João M. Saraiva ◽  
Gemma Arsequell ◽  
Gregori Valencia ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Kinetic Assay

scholarly journals DDIS-12. A FACILE, ROBUST AND PREDICTIVE IN VITRO BLOOD-BRAIN-BARRIER MODEL FOR HIGH-THROUGHPUT SCREENING AND DISCOVERY OF BRAIN-PENETRATING AGENTS

2016 ◽  
Vol 18 (suppl_6) ◽  
pp. vi49-vi50
Author(s):  
Choi-Fong Cho ◽  
Justin Wolfe ◽  
Colin Fazden ◽  
Kalvis Hornburg ◽  
E. Antonio Chiocca ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
High Throughput ◽  
High Throughput Screening ◽  
Brain Barrier ◽  
Blood Brain ◽  
Blood Brain Barrier Model ◽  
Barrier Model

scholarly journals New Approach for High-Throughput Screening of Drug Activity on Plasmodium Liver Stages

2006 ◽  
Vol 50 (4) ◽  
pp. 1586-1589 ◽  
Author(s):  
Audrey Gego ◽  
Olivier Silvie ◽  
Jean-François Franetich ◽  
Khemaïs Farhati ◽  
Laurent Hannoun ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
High Throughput ◽  
High Throughput Screening ◽  
Scanning System ◽  
New Approach ◽  
Drug Activity ◽  
Hepatic Cells ◽  
High Throughput Drug Screening ◽  
Prophylactic Drugs

ABSTRACT Plasmodium liver stages represent potential targets for antimalarial prophylactic drugs. Nevertheless, there is a lack of molecules active on these stages. We have now developed a new approach for the high-throughput screening of drug activity on Plasmodium liver stages in vitro, based on an infrared fluorescence scanning system. This method allowed us to count automatically and rapidly Plasmodium-infected hepatocytes, using different hepatic cells and different Plasmodium species, including Plasmodium falciparum. This new technique is well adapted for high-throughput drug screening and should facilitate the identification of new antimalarial compounds active on Plasmodium liver stages.

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