scholarly journals Identification of a Novel Laser Dye Substrate of Mammalian Cytochromes P450: Application in Rapid Kinetic Analysis, Inhibitor Screening, and Directed Evolution

2007 ◽  
Vol 12 (5) ◽  
pp. 677-682 ◽  
Author(s):  
Santosh Kumar
Keyword(s):  
Kinetic Analysis ◽  
Directed Evolution ◽  
High Throughput ◽  
Cumene Hydroperoxide ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Significant Activity ◽  
Laser Dye ◽  
Screening Assay ◽  
Inhibitor Screening ◽  
Activity Screening

The author sought to develop a high-throughput activity screening assay to carry out rapid kinetic analysis, inhibitor screening, and directed evolution of cytochrome P450 2C enzymes. Initially, of the 9 fluorescent substrates and 10 P450 2C enzymes tested, several P450 2C enzymes showed > 1 nmol/min/nmol P450 activity in cumene hydroperoxide (CuOOH)—supported reaction with a laser dye, 7-dimethylamino-4-trifluoromethylcoumarin (C152). A high-throughput steady-state kinetic analysis of the human P450 2C8, 2C9, and 2C19 showed 1) kcat = 3 to 6 min—1, 2) Km, CuOOH = 100 to 200 µM, and 3) S50, C152 = 10 to 20 µM in the CuOOH system. In addition, P450 2C9 and 2C19 showed a very high kcat (27 and 38 min—1, respectively) in the nicotinamide adenine dinucleotide phosphate (NADPH)—supported reaction. Subsequently, when mammalian P450s from the other subfamilies were tested, P450 2B1dH, 2B4dH, 2B5dH, 3A4, and 3A5 exhibited a significant activity in both CuOOH and NADPH systems. Furthermore, a high-throughput activity screening assay using whole-cell suspensions of the human P450 2C8, 2C9, and 2C19 was optimized. Overall, the data suggested that C152 can be used as a model substrate for mammalian P450s in CuOOH-supported reaction to perform rapid kinetic analysis, inhibitor screening, and directed evolution. ( Journal of Biomolecular Screening 2007:677-682)

scholarly journals Single-Round Remodeling of the Active Site of an Artificial Metalloenzyme using an Ultrahigh-Throughput Double Emulsion Screening Assay

2021 ◽  
Author(s):  
Jaicy Vallapurackal ◽  
Ariane Stucki ◽  
Alexandria Deliz Liang ◽  
Juliane Klehr ◽  
Petra S Dittrich ◽  
...  
Keyword(s):  
Directed Evolution ◽  
High Throughput ◽  
Double Emulsion ◽  
Cell Encapsulation ◽  
Optimization Procedure ◽  
Droplet Microfluidics ◽  
Screening Assay ◽  
Fluorescent Intensity ◽  
Double Emulsions ◽  
Artificial Metalloenzyme

The potential of high-throughput compartmentalization renders droplet microfluidics an attractive tool for directed evolution of enzymes as it permits maintenance of the phenotype-genotype linkage throughout the entire optimization procedure. In particular, water-in-oil-in-water double emulsions droplets (DEs) produced by microfluidics enable the analysis of reaction compartments at ultra-high-throughput using commercially available fluorescence-activated cell sorting (FACS) devices. Here we report a streamlined method applicable for the ultrahigh-throughput screening of an artificial metalloenzyme (ArM), an artificial deallylase (ADAse), in double emulsions. The DE-protocol was validated by screening a four hundred member, double-mutant streptavidin library for the CpRu-catalyzed uncaging of aminocoumarin. The most active variants, identified by next-generation sequencing of the sorted DE droplets with highest fluorescent intensity, are in good agreement with 96-well plate screening hits. These findings, thus, pave the way towards the systematic implementation of commercially available FACS for the directed evolution of metalloenzymes making ultrahigh-throughput screening more broadly accessible. The use of microfluidics for the formation of uniform compartments with precise control over reagents and cell encapsulation further facilitates the establishment of highly reliable quantitative assays.

Directed Evolution of P450 Fatty Acid Decarboxylases via High-Throughput Screening Towards Improved Catalytic Activity

2019 ◽  
Author(s):  
Huifang Xu ◽  
Weinan Liang ◽  
Linlin Ning ◽  
Yuanyuan Jiang ◽  
Wenxia Yang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Fatty Acid ◽  
Directed Evolution ◽  
High Throughput ◽  
High Throughput Screening ◽  
Colorimetric Detection ◽  
Screening Method ◽  
Random Mutagenesis ◽  
Direct Production ◽  
Consumption Activity

P450 fatty acid decarboxylases (FADCs) have recently been attracting considerable attention owing to their one-step direct production of industrially important 1-alkenes from biologically abundant feedstock free fatty acids under mild conditions. However, attempts to improve the catalytic activity of FADCs have met with little success. Protein engineering has been limited to selected residues and small mutant libraries due to lack of an effective high-throughput screening (HTS) method. Here, we devise a catalase-deficient <i>Escherichia coli</i> host strain and report an HTS approach based on colorimetric detection of H<sub>2</sub>O<sub>2</sub>-consumption activity of FADCs. Directed evolution enabled by this method has led to effective identification for the first time of improved FADC variants for medium-chain 1-alkene production from both DNA shuffling and random mutagenesis libraries. Advantageously, this screening method can be extended to other enzymes that stoichiometrically utilize H<sub>2</sub>O<sub>2</sub> as co-substrate.

High Throughput Screening Assay to Identify Modulators of IL-17 Expression

2018 ◽  
Vol 20 (9) ◽  
pp. 804-819 ◽  
Author(s):  
Mohamed Boudjelal ◽  
Ana Maria Ruiz-Avendano ◽  
Gonzalo Colmenarejo ◽  
Sergio A. Senar-Sancho ◽  
Ashley Barnes ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Screening Assay ◽  
High Throughput Screening Assay

scholarly journals A high-throughput screening assay based on automated microscopy for monitoring antibiotic susceptibility of Mycobacterium tuberculosis phenotypes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sadaf Kalsum ◽  
Blanka Andersson ◽  
Jyotirmoy Das ◽  
Thomas Schön ◽  
Maria Lerm
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Throughput ◽  
High Throughput Screening ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Imaging System ◽  
Aggregate Size ◽  
Live Cell ◽  
Screening Assay ◽  
High Throughput Screening Assay

Abstract Background Efficient high-throughput drug screening assays are necessary to enable the discovery of new anti-mycobacterial drugs. The purpose of our work was to develop and validate an assay based on live-cell imaging which can monitor the growth of two distinct phenotypes of Mycobacterium tuberculosis and to test their susceptibility to commonly used TB drugs. Results Both planktonic and cording phenotypes were successfully monitored as fluorescent objects using the live-cell imaging system IncuCyte S3, allowing collection of data describing distinct characteristics of aggregate size and growth. The quantification of changes in total area of aggregates was used to define IC50 and MIC values of selected TB drugs which revealed that the cording phenotype grew more rapidly and displayed a higher susceptibility to rifampicin. In checkerboard approach, testing pair-wise combinations of sub-inhibitory concentrations of drugs, rifampicin, linezolid and pretomanid demonstrated superior growth inhibition of cording phenotype. Conclusions Our results emphasize the efficiency of using automated live-cell imaging and its potential in high-throughput whole-cell screening to evaluate existing and search for novel antimycobacterial drugs.

scholarly journals Development of a High-Throughput Screening Assay to Identify Inhibitors of the SARS-CoV-2 Guanine-N7-Methyltransferase Using RapidFire Mass Spectrometry

2021 ◽  
pp. 247255522110006
Author(s):  
Lesley-Anne Pearson ◽  
Charlotte J. Green ◽  
De Lin ◽  
Alain-Pierre Petit ◽  
David W. Gray ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Mutational Analysis ◽  
Nonstructural Protein ◽  
Translation Efficiency ◽  
Screening Assay ◽  
High Throughput Screening Assay ◽  
Starting Point ◽  
Approved Drugs ◽  
High Throughput Assay

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents a significant threat to human health. Despite its similarity to related coronaviruses, there are currently no specific treatments for COVID-19 infection, and therefore there is an urgent need to develop therapies for this and future coronavirus outbreaks. Formation of the cap at the 5′ end of viral RNA has been shown to help coronaviruses evade host defenses. Nonstructural protein 14 (nsp14) is responsible for N7-methylation of the cap guanosine in coronaviruses. This enzyme is highly conserved among coronaviruses and is a bifunctional protein with both N7-methyltransferase and 3′-5′ exonuclease activities that distinguish nsp14 from its human equivalent. Mutational analysis of SARS-CoV nsp14 highlighted its role in viral replication and translation efficiency of the viral genome. In this paper, we describe the characterization and development of a high-throughput assay for nsp14 utilizing RapidFire technology. The assay has been used to screen a library of 1771 Food and Drug Administration (FDA)-approved drugs. From this, we have validated nitazoxanide as a selective inhibitor of the methyltransferase activity of nsp14. Although modestly active, this compound could serve as a starting point for further optimization.

scholarly journals Stress-Based High-Throughput Screening Assays to Identify Inhibitors of Cell Envelope Biogenesis

Antibiotics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 808
Author(s):  
Maurice Steenhuis ◽  
Corinne M. ten Hagen-Jongman ◽  
Peter van Ulsen ◽  
Joen Luirink
Keyword(s):  
Outer Membrane ◽  
High Throughput ◽  
Stress Responses ◽  
High Throughput Screening ◽  
Structural Integrity ◽  
Cell Envelope ◽  
Screening Assay ◽  
High Throughput Screening Assay ◽  
Compound Screening ◽  
Outer Membrane Biogenesis

The structural integrity of the Gram-negative cell envelope is guarded by several stress responses, such as the σE, Cpx and Rcs systems. Here, we report on assays that monitor these responses in E. coli upon addition of antibacterial compounds. Interestingly, compromised peptidoglycan synthesis, outer membrane biogenesis and LPS integrity predominantly activated the Rcs response, which we developed into a robust HTS (high-throughput screening) assay that is suited for phenotypic compound screening. Furthermore, by interrogating all three cell envelope stress reporters, and a reporter for the cytosolic heat-shock response as control, we found that inhibitors of specific envelope targets induce stress reporter profiles that are distinct in quality, amplitude and kinetics. Finally, we show that by using a host strain with a more permeable outer membrane, large-scaffold antibiotics can also be identified by the reporter assays. Together, the data suggest that stress profiling is a useful first filter for HTS aimed at inhibitors of cell envelope processes.

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