scholarly journals High throughput functional variant screens via in-vivo production of single-stranded DNA

2020 ◽  
Author(s):  
Max G. Schubert ◽  
Daniel B. Goodman ◽  
Timothy M. Wannier ◽  
Divjot Kaur ◽  
Fahim Farzadfard ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
High Throughput ◽  
Entire Genome ◽  
Single Stranded Dna ◽  
Functional Variant ◽  
Continuous Generation ◽  
Sources Of Variation ◽  
Targeted Deep Sequencing ◽  
High Throughput Screens

AbstractTremendous genetic variation exists in nature, but our ability to create and characterize individual genetic variants remains far more limited in scale. Likewise, engineering proteins and phenotypes requires the introduction of synthetic variants, but design of variants outpaces experimental measurement of variant effect. Here, we optimize efficient and continuous generation of precise genomic edits in Escherichia coli, via in-vivo production of single-stranded DNA by the targeted reverse-transcription activity of retrons. Greater than 90% editing efficiency can be obtained using this method, enabling multiplexed applications. We introduce Retron Library Recombineering (RLR), a system for high-throughput screens of variants, wherein the association of introduced edits with their retron elements enables a targeted deep sequencing phenotypic output. We use RLR for pooled, quantitative phenotyping of synthesized variants, characterizing antibiotic resistance alleles. We also perform RLR using sheared genomic DNA of an evolved bacterium, experimentally querying millions of sequences for antibiotic resistance variants. In doing so, we demonstrate that RLR is uniquely suited to utilize non-designed sources of variation. Pooled experiments using ssDNA produced in vivo thus present new avenues for exploring variation, both designed and not, across the entire genome.

scholarly journals High-throughput functional variant screens via in vivo production of single-stranded DNA

2021 ◽  
Vol 118 (18) ◽  
pp. e2018181118
Author(s):  
Max G. Schubert ◽  
Daniel B. Goodman ◽  
Timothy M. Wannier ◽  
Divjot Kaur ◽  
Fahim Farzadfard ◽  
...  
Keyword(s):  
High Throughput ◽  
Quantitative Measurement ◽  
Single Stranded Dna ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Functional Variant ◽  
Causal Variants ◽  
Targeted Deep Sequencing ◽  
Functional Screens

Creating and characterizing individual genetic variants remains limited in scale, compared to the tremendous variation both existing in nature and envisioned by genome engineers. Here we introduce retron library recombineering (RLR), a methodology for high-throughput functional screens that surpasses the scale and specificity of CRISPR-Cas methods. We use the targeted reverse-transcription activity of retrons to produce single-stranded DNA (ssDNA) in vivo, incorporating edits at >90% efficiency and enabling multiplexed applications. RLR simultaneously introduces many genomic variants, producing pooled and barcoded variant libraries addressable by targeted deep sequencing. We use RLR for pooled phenotyping of synthesized antibiotic resistance alleles, demonstrating quantitative measurement of relative growth rates. We also perform RLR using the sheared genomic DNA of an evolved bacterium, experimentally querying millions of sequences for causal variants, demonstrating that RLR is uniquely suited to utilize large pools of natural variation. Using ssDNA produced in vivo for pooled experiments presents avenues for exploring variation across the genome.

scholarly journals Identification and Validation of Small Molecules That Enhance Recombinant Adeno-associated Virus Transduction following High-Throughput Screens

2016 ◽  
Vol 90 (16) ◽  
pp. 7019-7031 ◽  
Author(s):  
Sarah C. Nicolson ◽  
Chengwen Li ◽  
Matthew L. Hirsch ◽  
Vincent Setola ◽  
R. Jude Samulski
Keyword(s):  
Gene Therapy ◽  
Gene Delivery ◽  
High Throughput ◽  
Adeno Associated Virus ◽  
Virus Gene ◽  
Diploid Cells ◽  
High Throughput Screens ◽  
Group 1

ABSTRACTWhile the recent success of adeno-associated virus (AAV)-mediated gene therapy in clinical trials is promising, challenges still face the widespread applicability of recombinant AAV(rAAV). A major goal is to enhance the transduction efficiency of vectors in order to achieve therapeutic levels of gene expression at a vector dose that is below the immunological response threshold. In an attempt to identify novel compounds that enhance rAAV transduction, we performed two high-throughput screens comprising 2,396 compounds. We identified 13 compounds that were capable of enhancing transduction, of which 12 demonstrated vector-specific effects and 1 could also enhance vector-independent transgene expression. Many of these compounds had similar properties and could be categorized into five groups: epipodophyllotoxins (group 1), inducers of DNA damage (group 2), effectors of epigenetic modification (group 3), anthracyclines (group 4), and proteasome inhibitors (group 5). We optimized dosing for the identified compounds in several immortalized human cell lines as well as normal diploid cells. We found that the group 1 epipodophyllotoxins (teniposide and etoposide) consistently produced the greatest transduction enhancement. We also explored transduction enhancement among single-stranded, self-complementary, and fragment vectors and found that the compounds could impact fragmented rAAV2 transduction to an even greater extent than single-stranded vectors.In vivoanalysis of rAAV2 and all of the clinically relevant compounds revealed that, consistent with ourin vitroresults, teniposide exhibited the greatest level of transduction enhancement. Finally, we explored the capability of teniposide to enhance transduction of fragment vectorsin vivousing an AAV8 capsid that is known to exhibit robust liver tropism. Consistent with ourin vitroresults, teniposide coadministration greatly enhanced fragmented rAAV8 transduction at 48 h and 8 days. This study provides a foundation based on the rAAV small-molecule screen methodology, which is ideally used for more-diverse libraries of compounds that can be tested for potentiating rAAV transduction.IMPORTANCEThis study seeks to enhance the capability of adeno-associated viral vectors for therapeutic gene delivery applicable to the treatment of diverse diseases. To do this, a comprehensive panel of FDA-approved drugs were tested in human cells and in animal models to determine if they increased adeno-associated virus gene delivery. The results demonstrate that particular groups of drugs enhance adeno-associated virus gene delivery by unknown mechanisms. In particular, the enhancement of gene delivery was approximately 50 to 100 times better with than without teniposide, a compound that is also used as chemotherapy for cancer. Collectively, these results highlight the potential for FDA-approved drug enhancement of adeno-associated virus gene therapy, which could result in safe and effective treatments for diverse acquired or genetic diseases.

Union is strength: target-based and whole-cell high throughput screens in antibacterial discovery

2021 ◽  
Author(s):  
Cristina Landeta ◽  
Adrian Mejia-Santana
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Enzymatic Reactions ◽  
Whole Cell ◽  
Bacterial Physiology ◽  
Whole Cells ◽  
Discovery Research ◽  
High Throughput Screens

Antimicrobial resistance is one of the greatest global health challenges today. For over three decades antibacterial discovery research and development has been focused on cell-based and target-based high throughput assays. Target-based screens use diagnostic enzymatic reactions to look for molecules that can bind directly and inhibit the target. Target-based screens are only applied to proteins that can be successfully expressed, purified and the activity of which can be effectively measured using a biochemical assay. Often times the molecules found in these in vitro screens are not active in cells due to poor permeability or efflux. On the other hand, cell-based screens use whole cells and look for growth inhibition. These screens give higher number of hits than target-based assays and can simultaneously test many targets of one process or pathway in their physiological context. Both strategies have pros and cons when used separately. In the past decade and a half our increasing knowledge of bacterial physiology has led to the development of innovative and sophisticated technologies to perform high throughput screening combining these two strategies and thus minimizing their disadvantages. In this review we discuss recent examples of high throughput approaches that used both target-based and whole-cell screening to find new antibacterials, the new insights they have provided and how this knowledge can be applied to other in vivo validated targets to develop new antimicrobials.

scholarly journals High-Throughput Fluorescence Polarization Method for Identification of FKBP12 Ligands

2002 ◽  
Vol 7 (6) ◽  
pp. 526-530 ◽  
Author(s):  
S. Bollini ◽  
J. J. Herbst ◽  
G. T. Gaughan ◽  
T. A. Verdoorn ◽  
J. Ditta ◽  
...  
Keyword(s):  
High Throughput ◽  
Fluorescence Polarization ◽  
High Throughput Screening ◽  
Metal Ion ◽  
Gel Filtration ◽  
Immunosuppressive Drug ◽  
Fluorescence Polarization Assay ◽  
High Throughput Screens

FKBP12 is best known as the target of the widely used immunosuppressive drug FK506 but may also play a role in neuronal survival. Nonimmunosuppressive ligands of FKBP12 have been shown to have neuroprotective and neuroregenerative activity both in vitro and in vivo, stimulating interest in the development of high-throughput screens to rapidly identify novel ligands. FKBP12 was expressed as a His6-fusion in bacteria and purified by metal ion affinity and gel filtration chromatography. A high-throughput fluorescence polarization assay was developed to identify novel ligands of FKBP12. Dissociation constant values of known FKBP12 ligands measured by the new method agreed closely with Ki values obtained by assaying inhibition of the rotamase activity of the enzyme. The fluorescence polarization assay is rapid, robust, and inexpensive and does not generate radioactive waste. It is very well suited for high-throughput screening efforts.

scholarly journals AtomNet PoseRanker: Enriching Ligand Pose Quality for Dynamic Proteins in Virtual High Throughput Screens

2021 ◽  
Author(s):  
Kate Stafford ◽  
Brandon M. Anderson ◽  
Jon Sorenson ◽  
Henry van den Bedem
Keyword(s):  
Drug Discovery ◽  
High Throughput ◽  
High Throughput Screening ◽  
Conformational Ensemble ◽  
Binding Modes ◽  
Convolutional Network ◽  
In Silico Docking ◽  
High Throughput Screens ◽  
Affinity Score

Structure-based, virtual High Throughput Screening (vHTS) methods for predicting ligand activity in drug discovery are important when there are no or relatively few known compounds that interact with a therapeutic target of interest. State-of-the-art computational vHTS necessarily relies on effective methods for pose sampling and docking to generate an accurate affinity score from the docked poses. However, proteins are dynamic; in vivo, ligands bind to a conformational ensemble. In silico docking to the single conformation represented by a crystal structure can adversely affect the pose quality. Here we introduce AtomNet PoseRanker, a graph convolutional network trained to identify, and re-rank crystal-like ligand poses from a sampled ensemble of protein conformations and ligand poses. In contrast to conventional vHTS methods that incorporate receptor flexibility, a deep learning approach can internalize valid cognate and non-cognate binding modes corresponding to distinct receptor conformations. AtomNet PoseRanker significantly enriched pose quality in docking to cognate and non-cognate receptors of the PDBbind v2019 dataset. Improved pose rankings that better represent experimentally observed ligand binding modes improve hit rates in vHTS campaigns, and thereby advance computational drug discovery, especially for novel therapeutic targets or novel binding sites.

scholarly journals Transitioning pharmacoperones to therapeutic use: In vivo proof-of-principle and design of high throughput screens

2014 ◽  
Vol 83 ◽  
pp. 38-51 ◽  
Author(s):  
P. Michael Conn ◽  
David C. Smithson ◽  
Peter S. Hodder ◽  
M. David Stewart ◽  
Richard R. Behringer ◽  
...  
Keyword(s):  
High Throughput ◽  
Therapeutic Use ◽  
High Throughput Screens ◽  
Proof Of Principle

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.

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