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1.
PLoS One ; 17(5): e0268767, 2022.
Article in English | MEDLINE | ID: covidwho-1862275

ABSTRACT

Since the outbreak of the COVID-19 pandemic, widespread infections have allowed SARS-CoV-2 to evolve in human, leading to the emergence of multiple circulating variants. Some of these variants show increased resistance to vaccine-elicited immunity, convalescent plasma, or monoclonal antibodies. In particular, mutations in the SARS-CoV-2 spike have drawn attention. To facilitate the isolation of neutralizing antibodies and the monitoring of vaccine effectiveness against these variants, we designed and produced biotin-labeled molecular probes of variant SARS-CoV-2 spikes and their subdomains, using a structure-based construct design that incorporated an N-terminal purification tag, a specific amino acid sequence for protease cleavage, the variant spike-based region of interest, and a C-terminal sequence targeted by biotin ligase. These probes could be produced by a single step using in-process biotinylation and purification. We characterized the physical properties and antigenicity of these probes, comprising the N-terminal domain (NTD), the receptor-binding domain (RBD), the RBD and subdomain 1 (RBD-SD1), and the prefusion-stabilized spike ectodomain (S2P) with sequences from SARS-CoV-2 variants of concern or of interest, including variants Alpha, Beta, Gamma, Epsilon, Iota, Kappa, Delta, Lambda, Mu, and Omicron. We functionally validated probes by using yeast expressing a panel of nine SARS-CoV-2 spike-binding antibodies and confirmed sorting capabilities of variant probes using yeast displaying libraries of plasma antibodies from COVID-19 convalescent donors. We deposited these constructs to Addgene to enable their dissemination. Overall, this study describes a matrix of SARS-CoV-2 variant molecular probes that allow for assessment of immune responses, identification of serum antibody specificity, and isolation and characterization of neutralizing antibodies.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , Biotin , COVID-19/therapy , Humans , Immunization, Passive , Molecular Probes , Neutralization Tests , Pandemics , SARS-CoV-2/genetics , Saccharomyces cerevisiae/genetics , Spike Glycoprotein, Coronavirus
2.
Front Biosci (Landmark Ed) ; 27(3): 93, 2022 03 09.
Article in English | MEDLINE | ID: covidwho-1766334

ABSTRACT

BACKGROUND: Inhibition of human topoisomerase I (TOP1) by camptothecin and topotecan has been shown to reduce excessive transcription of PAMP (Pathogen-Associated Molecular Pattern)-induced genes in prior studies, preventing death from sepsis in animal models of bacterial and SARS-CoV-2 infections. The TOP1 catalytic activity likely resolves the topological constraints on DNA that encodes these genes to facilitate the transcription induction that leads to excess inflammation. The increased accumulation of TOP1-DNA covalent complex (TOP1cc) following DNA cleavage is the basis for the anticancer efficacy of the TOP1 poisons developed for anticancer treatment. The potential cytotoxicity and mutagenicity of TOP1 targeting cancer drugs pose serious concerns for employing them as therapies in sepsis prevention. METHODS: In this study we set up a novel yeast-based screening system that employs yeast strains expressing wild-type or a dominant lethal mutant recombinant human TOP1. The effect of test compounds on growth is monitored with and without overexpression of the recombinant human TOP1. RESULTS: This yeast-based screening system can identify human TOP1 poisons for anticancer efficacy as well as TOP1 suppressors that can inhibit TOP1 DNA binding or cleavage activity in steps prior to the formation of the TOP1cc. CONCLUSIONS: This yeast-based screening system can distinguish between TOP1 suppressors and TOP1 poisons. The assay can also identify compounds that are likely to be cytotoxic based on their effect on yeast cell growth that is independent of recombinant human TOP1 overexpression.


Subject(s)
COVID-19 , Poisons , Animals , DNA Topoisomerases, Type I/chemistry , DNA Topoisomerases, Type I/genetics , DNA Topoisomerases, Type I/metabolism , Humans , SARS-CoV-2 , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism
3.
Protein Expr Purif ; 190: 106003, 2022 02.
Article in English | MEDLINE | ID: covidwho-1474960

ABSTRACT

SARS-CoV-2 protein subunit vaccines are currently being evaluated by multiple manufacturers to address the global vaccine equity gap, and need for low-cost, easy to scale, safe, and effective COVID-19 vaccines. In this paper, we report on the generation of the receptor-binding domain RBD203-N1 yeast expression construct, which produces a recombinant protein capable of eliciting a robust immune response and protection in mice against SARS-CoV-2 challenge infections. The RBD203-N1 antigen was expressed in the yeast Pichia pastoris X33. After fermentation at the 5 L scale, the protein was purified by hydrophobic interaction chromatography followed by anion exchange chromatography. The purified protein was characterized biophysically and biochemically, and after its formulation, the immunogenicity was evaluated in mice. Sera were evaluated for their efficacy using a SARS-CoV-2 pseudovirus assay. The RBD203-N1 protein was expressed with a yield of 492.9 ± 3.0 mg/L of fermentation supernatant. A two-step purification process produced a >96% pure protein with a recovery rate of 55 ± 3% (total yield of purified protein: 270.5 ± 13.2 mg/L fermentation supernatant). The protein was characterized to be a homogeneous monomer that showed a well-defined secondary structure, was thermally stable, antigenic, and when adjuvanted on Alhydrogel in the presence of CpG it was immunogenic and induced high levels of neutralizing antibodies against SARS-CoV-2 pseudovirus. The characteristics of the RBD203-N1 protein-based vaccine show that this candidate is another well suited RBD-based construct for technology transfer to manufacturing entities and feasibility of transition into the clinic to evaluate its immunogenicity and safety in humans.


Subject(s)
COVID-19 Vaccines , Gene Expression , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Animals , COVID-19 Vaccines/chemistry , COVID-19 Vaccines/genetics , COVID-19 Vaccines/pharmacology , Humans , Mice , Protein Domains , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/pharmacology , SARS-CoV-2/chemistry , SARS-CoV-2/genetics , Saccharomyces cerevisiae/chemistry , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/pharmacology
4.
Science ; 374(6571): 1099-1106, 2021 Nov 26.
Article in English | MEDLINE | ID: covidwho-1467657

ABSTRACT

Molecular virology tools are critical for basic studies of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and for developing new therapeutics. Experimental systems that do not rely on viruses capable of spread are needed for potential use in lower-containment settings. In this work, we use a yeast-based reverse genetics system to develop spike-deleted SARS-CoV-2 self-replicating RNAs. These noninfectious self-replicating RNAs, or replicons, can be trans-complemented with viral glycoproteins to generate replicon delivery particles for single-cycle delivery into a range of cell types. This SARS-CoV-2 replicon system represents a convenient and versatile platform for antiviral drug screening, neutralization assays, host factor validation, and viral variant characterization.


Subject(s)
RNA, Viral/genetics , Replicon/physiology , SARS-CoV-2/genetics , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Antiviral Agents/pharmacology , Cell Line , Humans , Interferons/pharmacology , Microbial Sensitivity Tests , Mutation , Plasmids , RNA, Viral/metabolism , Replicon/genetics , Reverse Genetics , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Saccharomyces cerevisiae/genetics , Spike Glycoprotein, Coronavirus/genetics , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/metabolism , Virion/genetics , Virion/physiology , Virus Replication
5.
STAR Protoc ; 2(4): 100869, 2021 12 17.
Article in English | MEDLINE | ID: covidwho-1433914

ABSTRACT

Here, we describe a protocol to identify escape mutants on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) receptor-binding domain (RBD) using a yeast screen combined with deep mutational scanning. Over 90% of all potential single S RBD escape mutants can be identified for monoclonal antibodies that directly compete with angiotensin-converting enzyme 2 for binding. Six to 10 antibodies can be assessed in parallel. This approach has been shown to determine escape mutants that are consistent with more laborious SARS-CoV-2 pseudoneutralization assays. For complete details on the use and execution of this protocol, please refer to Francino-Urdaniz et al. (2021).


Subject(s)
Angiotensin-Converting Enzyme 2/genetics , COVID-19/genetics , DNA Mutational Analysis/methods , Mutation , SARS-CoV-2/genetics , Saccharomyces cerevisiae/metabolism , Spike Glycoprotein, Coronavirus/genetics , Angiotensin-Converting Enzyme 2/metabolism , Binding Sites , COVID-19/metabolism , COVID-19/virology , Humans , Saccharomyces cerevisiae/genetics , Spike Glycoprotein, Coronavirus/metabolism
6.
Nat Commun ; 12(1): 4918, 2021 08 13.
Article in English | MEDLINE | ID: covidwho-1397870

ABSTRACT

Ribosomal RNA genes (rDNA) are highly unstable and susceptible to rearrangement due to their repetitive nature and active transcriptional status. Sequestration of rDNA in the nucleolus suppresses uncontrolled recombination. However, broken repeats must be first released to the nucleoplasm to allow repair by homologous recombination. Nucleolar release of broken rDNA repeats is conserved from yeast to humans, but the underlying molecular mechanisms are currently unknown. Here we show that DNA damage induces phosphorylation of the CLIP-cohibin complex, releasing membrane-tethered rDNA from the nucleolus in Saccharomyces cerevisiae. Downstream of phosphorylation, SUMOylation of CLIP-cohibin is recognized by Ufd1 via its SUMO-interacting motif, which targets the complex for disassembly through the Cdc48/p97 chaperone. Consistent with a conserved mechanism, UFD1L depletion in human cells impairs rDNA release. The dynamic and regulated assembly and disassembly of the rDNA-tethering complex is therefore a key determinant of nucleolar rDNA release and genome integrity.


Subject(s)
Cell Nucleolus/genetics , DNA Repair , DNA, Ribosomal/genetics , Saccharomyces cerevisiae Proteins/genetics , Small Ubiquitin-Related Modifier Proteins/genetics , Valosin Containing Protein/genetics , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Nucleolus/metabolism , DNA Damage , DNA, Ribosomal/metabolism , Humans , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mutation , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Phosphorylation , Protein Binding , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Small Ubiquitin-Related Modifier Proteins/metabolism , Sumoylation , Two-Hybrid System Techniques , Valosin Containing Protein/metabolism
7.
Cell Mol Immunol ; 18(8): 1847-1860, 2021 08.
Article in English | MEDLINE | ID: covidwho-1387308

ABSTRACT

CD4+ T cells orchestrate adaptive immune responses via binding of antigens to their receptors through specific peptide/MHC-II complexes. To study these responses, it is essential to identify protein-derived MHC-II peptide ligands that constitute epitopes for T cell recognition. However, generating cells expressing single MHC-II alleles and isolating these proteins for use in peptide elution or binding studies is time consuming. Here, we express human MHC alleles (HLA-DR4 and HLA-DQ6) as native, noncovalent αß dimers on yeast cells for direct flow cytometry-based screening of peptide ligands from selected antigens. We demonstrate rapid, accurate identification of DQ6 ligands from pre-pro-hypocretin, a narcolepsy-related immunogenic target. We also identify 20 DR4-binding SARS-CoV-2 spike peptides homologous to SARS-CoV-1 epitopes, and one spike peptide overlapping with the reported SARS-CoV-2 epitope recognized by CD4+ T cells from unexposed individuals carrying DR4 subtypes. Our method is optimized for immediate application upon the emergence of novel pathogens.


Subject(s)
CD4-Positive T-Lymphocytes/metabolism , COVID-19/metabolism , Epitopes, T-Lymphocyte/metabolism , HLA-DQ Antigens/metabolism , HLA-DR4 Antigen/metabolism , Saccharomyces cerevisiae/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Two-Hybrid System Techniques , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/virology , COVID-19/genetics , COVID-19/immunology , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Flow Cytometry , HLA-DQ Antigens/genetics , HLA-DQ Antigens/immunology , HLA-DR4 Antigen/genetics , HLA-DR4 Antigen/immunology , Ligands , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/immunology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
8.
Cell Host Microbe ; 29(1): 44-57.e9, 2021 01 13.
Article in English | MEDLINE | ID: covidwho-1385265

ABSTRACT

Antibodies targeting the SARS-CoV-2 spike receptor-binding domain (RBD) are being developed as therapeutics and are a major contributor to neutralizing antibody responses elicited by infection. Here, we describe a deep mutational scanning method to map how all amino-acid mutations in the RBD affect antibody binding and apply this method to 10 human monoclonal antibodies. The escape mutations cluster on several surfaces of the RBD that broadly correspond to structurally defined antibody epitopes. However, even antibodies targeting the same surface often have distinct escape mutations. The complete escape maps predict which mutations are selected during viral growth in the presence of single antibodies. They further enable the design of escape-resistant antibody cocktails-including cocktails of antibodies that compete for binding to the same RBD surface but have different escape mutations. Therefore, complete escape-mutation maps enable rational design of antibody therapeutics and assessment of the antigenic consequences of viral evolution.


Subject(s)
SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/metabolism , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Binding Sites , Epitopes/immunology , Gene Library , High-Throughput Nucleotide Sequencing , Humans , Protein Domains , SARS-CoV-2/genetics , Saccharomyces cerevisiae/genetics , Spike Glycoprotein, Coronavirus/chemistry
9.
Adv Protein Chem Struct Biol ; 124: 275-309, 2021.
Article in English | MEDLINE | ID: covidwho-1375869

ABSTRACT

The discovery and development of a new drug is a complex, time consuming and costly process that typically takes over 10 years and costs around 1 billion dollars from bench to market. This scenario makes the discovery of novel drugs targeting neglected tropical diseases (NTDs), which afflict in particular people in low-income countries, prohibitive. Despite the intensive use of High-Throughput Screening (HTS) in the past decades, the speed with which new drugs come to the market has remained constant, generating doubts about the efficacy of this approach. Here we review a few of the yeast-based high-throughput approaches that can work synergistically with parasite-based, in vitro, or in silico methods to identify and optimize novel antiparasitic compounds. These yeast-based methods range from HTP screens to identify novel hits against promising parasite kinase targets to the identification of potential antiparasitic kinase inhibitors extracted from databases of yeast chemical genetic screens.


Subject(s)
Drug Discovery , Neglected Diseases , Protein Kinase Inhibitors , Protein Kinases , Saccharomyces cerevisiae , Drug Evaluation, Preclinical , Humans , Neglected Diseases/drug therapy , Neglected Diseases/enzymology , Neglected Diseases/genetics , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/therapeutic use , Protein Kinases/genetics , Protein Kinases/metabolism , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/genetics
10.
Biol Cell ; 113(7): 311-328, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1294968

ABSTRACT

BACKGROUND INFORMATION: Comprehensive libraries of plasmids for SARS-CoV-2 proteins with various tags (e.g., Strep, HA, Turbo) are now available. They enable the identification of numerous potential protein-protein interactions between the SARS-CoV-2 virus and host proteins. RESULTS: We present here a large library of SARS CoV-2 protein constructs fused with green and red fluorescent proteins and their initial characterisation in various human cell lines including lung epithelial cell models (A549, BEAS-2B), as well as in budding yeast. The localisation of a few SARS-CoV-2 proteins matches their proposed interactions with host proteins. These include the localisation of Nsp13 to the centrosome, Orf3a to late endosomes and Orf9b to mitochondria. CONCLUSIONS AND SIGNIFICANCE: This library should facilitate further cellular investigations, notably by imaging techniques.


Subject(s)
COVID-19/virology , Peptide Library , SARS-CoV-2/metabolism , Viral Proteins/metabolism , A549 Cells , Cell Line , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Host Microbial Interactions/physiology , Humans , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Microscopy, Fluorescence , Protein Interaction Domains and Motifs , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , SARS-CoV-2/genetics , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Time-Lapse Imaging , Viral Proteins/genetics
11.
Curr Genet ; 67(5): 755-759, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1216214

ABSTRACT

With the current COVID-19 pandemic, we all realized how important interactions are. Interactions are everywhere. At the cellular level, protein interactions play a key role and their ensemble, also called interactome, is often referred as the basic building blocks of life. Given its importance, the maintenance of the integrity of the interactome is a real challenge in the cell. Many events during evolution can disrupt interactomes and potentially result in different characteristics for the organisms. However, the molecular underpinnings of changes in interactions at the cellular level are still largely unexplored. Among the perturbations, hybridization puts in contact two different interactomes, which may lead to many changes in the protein interaction network of the hybrid, including gains and losses of interactions. We recently investigated the fate of the interactomes after hybridization between yeast species using a comparative proteomics approach. A large-scale conservation of the interactions was observed in hybrids, but we also noticed the presence of proteostasis-related changes. This suggests that, despite a general robustness, small differences may accumulate in hybrids and perturb their protein physiology. Here, we summarize our work with a broader perspective on the importance of interactions.


Subject(s)
Fungal Proteins/metabolism , Hybridization, Genetic , Protein Interaction Maps , Saccharomyces cerevisiae/metabolism , Saccharomyces/metabolism , Animals , Fungal Proteins/chemistry , Fungal Proteins/genetics , Proteomics , Saccharomyces/chemistry , Saccharomyces/classification , Saccharomyces/genetics , Saccharomyces cerevisiae/chemistry , Saccharomyces cerevisiae/genetics
12.
Hum Vaccin Immunother ; 17(8): 2356-2366, 2021 08 03.
Article in English | MEDLINE | ID: covidwho-1180453

ABSTRACT

There is an urgent need for an accessible and low-cost COVID-19 vaccine suitable for low- and middle-income countries. Here, we report on the development of a SARS-CoV-2 receptor-binding domain (RBD) protein, expressed at high levels in yeast (Pichia pastoris), as a suitable vaccine candidate against COVID-19. After introducing two modifications into the wild-type RBD gene to reduce yeast-derived hyperglycosylation and improve stability during protein expression, we show that the recombinant protein, RBD219-N1C1, is equivalent to the wild-type RBD recombinant protein (RBD219-WT) in an in vitro ACE-2 binding assay. Immunogenicity studies of RBD219-N1C1 and RBD219-WT proteins formulated with Alhydrogel® were conducted in mice, and, after two doses, both the RBD219-WT and RBD219-N1C1 vaccines induced high levels of binding IgG antibodies. Using a SARS-CoV-2 pseudovirus, we further showed that sera obtained after a two-dose immunization schedule of the vaccines were sufficient to elicit strong neutralizing antibody titers in the 1:1,000 to 1:10,000 range, for both antigens tested. The vaccines induced IFN-γ IL-6, and IL-10 secretion, among other cytokines. Overall, these data suggest that the RBD219-N1C1 recombinant protein, produced in yeast, is suitable for further evaluation as a human COVID-19 vaccine, in particular, in an Alhydrogel® containing formulation and possibly in combination with other immunostimulants.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Animals , Antibodies, Neutralizing , Antibodies, Viral , COVID-19 Vaccines , Humans , Mice , Mice, Inbred BALB C , Protein Domains , SARS-CoV-2 , Saccharomyces cerevisiae/genetics , Saccharomycetales , T-Lymphocytes
13.
Methods Mol Biol ; 2203: 205-221, 2020.
Article in English | MEDLINE | ID: covidwho-729908

ABSTRACT

We have developed a screening system using the yeast Saccharomyces cerevisiae to identify eukaryotic genes involved in the replication of mammalian viruses. Yeast come with various advantages, but in the context of coronavirus research and the system outlined here, they are simple and easy to work with and can be used at biosafety level 2. The system involves inducible expression of individual viral proteins and identification of detrimental phenotypes in the yeast. Yeast knockout and overexpression libraries can then be used for genome-wide screening of host proteins that provide a suppressor phenotype. From the yeast hits, a narrowed list of candidate genes can be produced to investigate for roles in viral replication. Since the system only requires expression of viral proteins, it can be used for any current or emerging virus, regardless of biocontainment requirements and ability to culture the virus. In this chapter, we will outline the protocols that can be used to take advantage of S. cerevisiae as a tool to advance understanding of how viruses interact with eukaryotic cells.


Subject(s)
Coronavirus/physiology , Coronavirus/pathogenicity , Host-Pathogen Interactions/physiology , Saccharomyces cerevisiae/genetics , Plasmids , Viral Proteins/genetics , Viral Proteins/isolation & purification , Virus Replication
14.
Proc Natl Acad Sci U S A ; 118(14)2021 04 06.
Article in English | MEDLINE | ID: covidwho-1142537

ABSTRACT

When addressing a genomic question, having a reliable and adequate reference genome is of utmost importance. This drives the necessity to refine and customize reference genomes (RGs). Our laboratory has recently developed a strategy, the Perfect Match Genomic Landscape (PMGL), to detect variation between genomes [K. Palacios-Flores et al. Genetics 208, 1631-1641 (2018)]. The PMGL is precise and sensitive and, in contrast to most currently used algorithms, is nonstatistical in nature. Here we demonstrate the power of PMGL to refine and customize RGs. As a proof-of-concept, we refined different versions of the Saccharomyces cerevisiae RG. We applied the automatic PMGL pipeline to refine the genomes of microorganisms belonging to the three domains of life: the archaea Methanococcus maripaludis and Pyrococcus furiosus; the bacteria Escherichia coli, Staphylococcus aureus, and Bacillus subtilis; and the eukarya Schizosaccharomyces pombe, Aspergillus oryzae, and several strains of Saccharomyces paradoxus. We analyzed the reference genome of the virus SARS-CoV-2 and previously published viral genomes from patients' samples with COVID-19. We performed a mutation-accumulation experiment in E. coli and show that the PMGL strategy can detect specific mutations generated at any desired step of the whole procedure. We propose that PMGL can be used as a final step for the refinement and customization of any haploid genome, independently of the strategies and algorithms used in its assembly.


Subject(s)
Genetic Variation , Genome, Microbial , Genomics/methods , SARS-CoV-2/genetics , Algorithms , Mutation Accumulation , Proof of Concept Study , Saccharomyces cerevisiae/genetics
15.
Biol Cell ; 113(7): 311-328, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1119222

ABSTRACT

BACKGROUND INFORMATION: Comprehensive libraries of plasmids for SARS-CoV-2 proteins with various tags (e.g., Strep, HA, Turbo) are now available. They enable the identification of numerous potential protein-protein interactions between the SARS-CoV-2 virus and host proteins. RESULTS: We present here a large library of SARS CoV-2 protein constructs fused with green and red fluorescent proteins and their initial characterisation in various human cell lines including lung epithelial cell models (A549, BEAS-2B), as well as in budding yeast. The localisation of a few SARS-CoV-2 proteins matches their proposed interactions with host proteins. These include the localisation of Nsp13 to the centrosome, Orf3a to late endosomes and Orf9b to mitochondria. CONCLUSIONS AND SIGNIFICANCE: This library should facilitate further cellular investigations, notably by imaging techniques.


Subject(s)
COVID-19/virology , Peptide Library , SARS-CoV-2/metabolism , Viral Proteins/metabolism , A549 Cells , Cell Line , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Host Microbial Interactions/physiology , Humans , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Microscopy, Fluorescence , Protein Interaction Domains and Motifs , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , SARS-CoV-2/genetics , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Time-Lapse Imaging , Viral Proteins/genetics
16.
Int J Mol Sci ; 21(19)2020 Sep 28.
Article in English | MEDLINE | ID: covidwho-963280

ABSTRACT

Some years inspire more hindsight reflection and future-gazing than others. This is even more so in 2020 with its evocation of perfect vision and the landmark ring to it. However, no futurist can reliably predict what the world will look like the next time that a year's first two digits will match the second two digits-a numerical pattern that only occurs once in a century. As we leap into a new decade, amid uncertainties triggered by unforeseen global events-such as the outbreak of a worldwide pandemic, the accompanying economic hardship, and intensifying geopolitical tensions-it is important to note the blistering pace of 21st century technological developments indicate that while hindsight might be 20/20, foresight is 50/50. The history of science shows us that imaginative ideas, research excellence, and collaborative innovation can, for example, significantly contribute to the economic, cultural, social, and environmental recovery of a post-COVID-19 world. This article reflects on a history of yeast research to indicate the potential that arises from advances in science, and how this can contribute to the ongoing recovery and development of human society. Future breakthroughs in synthetic genomics are likely to unlock new avenues of impactful discoveries and solutions to some of the world's greatest challenges.


Subject(s)
Disease Outbreaks/prevention & control , Genetic Engineering/methods , Genome, Fungal , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Synthetic Biology/methods , Saccharomyces cerevisiae/classification
17.
Proc Natl Acad Sci U S A ; 117(48): 30687-30698, 2020 12 01.
Article in English | MEDLINE | ID: covidwho-922313

ABSTRACT

The SARS-CoV-2 pandemic has made it clear that we have a desperate need for antivirals. We present work that the mammalian SKI complex is a broad-spectrum, host-directed, antiviral drug target. Yeast suppressor screening was utilized to find a functional genetic interaction between proteins from influenza A virus (IAV) and Middle East respiratory syndrome coronavirus (MERS-CoV) with eukaryotic proteins that may be potential host factors involved in replication. This screening identified the SKI complex as a potential host factor for both viruses. In mammalian systems siRNA-mediated knockdown of SKI genes inhibited replication of IAV and MERS-CoV. In silico modeling and database screening identified a binding pocket on the SKI complex and compounds predicted to bind. Experimental assays of those compounds identified three chemical structures that were antiviral against IAV and MERS-CoV along with the filoviruses Ebola and Marburg and two further coronaviruses, SARS-CoV and SARS-CoV-2. The mechanism of antiviral activity is through inhibition of viral RNA production. This work defines the mammalian SKI complex as a broad-spectrum antiviral drug target and identifies lead compounds for further development.


Subject(s)
Antiviral Agents/pharmacology , Coronavirus/drug effects , Filoviridae/drug effects , Host-Pathogen Interactions/drug effects , Multiprotein Complexes/metabolism , Orthomyxoviridae/drug effects , Cell Line , Genes, Suppressor , Models, Molecular , Molecular Targeted Therapy , Protein Binding , RNA, Small Interfering/metabolism , RNA, Viral/genetics , RNA, Viral/metabolism , Saccharomyces cerevisiae/genetics , Viral Proteins/metabolism , Virus Replication/drug effects
18.
Methods Mol Biol ; 2203: 167-184, 2020.
Article in English | MEDLINE | ID: covidwho-761352

ABSTRACT

The Escherichia coli and vaccinia virus-based reverse genetics systems have been widely applied for the manipulation and engineering of coronavirus genomes. These systems, however, present several limitations and are sometimes difficult to establish in a timely manner for (re-)emerging viruses. In this chapter, we present a new universal reverse genetics platform for the assembly and engineering of infectious full-length cDNAs using yeast-based transformation-associated recombination cloning. This novel assembly method not only results in stable coronavirus infectious full-length cDNAs cloned in the yeast Saccharomyces cerevisiae but also fosters and accelerates the manipulation of their genomes. Such a platform is widely applicable for the scientific community, as it requires no specific equipment and can be performed in a standard laboratory setting. The protocol described can be easily adapted to virtually all known or emerging coronaviruses, such as Middle East respiratory syndrome coronavirus (MERS-CoV).


Subject(s)
Coronavirus/genetics , DNA, Complementary/genetics , Genomics/methods , Saccharomyces cerevisiae/genetics , Animals , Cell Line , Coronavirus/pathogenicity , Homologous Recombination , Middle East Respiratory Syndrome Coronavirus/genetics , Middle East Respiratory Syndrome Coronavirus/pathogenicity
19.
Nature ; 585(7826): 614-619, 2020 09.
Article in English | MEDLINE | ID: covidwho-744380

ABSTRACT

Tropane alkaloids from nightshade plants are neurotransmitter inhibitors that are used for treating neuromuscular disorders and are classified as essential medicines by the World Health Organization1,2. Challenges in global supplies have resulted in frequent shortages of these drugs3,4. Further vulnerabilities in supply chains have been revealed by events such as the Australian wildfires5 and the COVID-19 pandemic6. Rapidly deployable production strategies that are robust to environmental and socioeconomic upheaval7,8 are needed. Here we engineered baker's yeast to produce the medicinal alkaloids hyoscyamine and scopolamine, starting from simple sugars and amino acids. We combined functional genomics to identify a missing pathway enzyme, protein engineering to enable the functional expression of an acyltransferase via trafficking to the vacuole, heterologous transporters to facilitate intracellular routing, and strain optimization to improve titres. Our integrated system positions more than twenty proteins adapted from yeast, bacteria, plants and animals across six sub-cellular locations to recapitulate the spatial organization of tropane alkaloid biosynthesis in plants. Microbial biosynthesis platforms can facilitate the discovery of tropane alkaloid derivatives as new therapeutic agents for neurological disease and, once scaled, enable robust and agile supply of these essential medicines.


Subject(s)
Alkaloids/biosynthesis , Alkaloids/supply & distribution , Hyoscyamine/biosynthesis , Saccharomyces cerevisiae/metabolism , Scopolamine/metabolism , Acyltransferases/genetics , Acyltransferases/metabolism , Animals , Atropa belladonna/enzymology , Atropine Derivatives/metabolism , Biological Transport , Datura/enzymology , Glucosides/biosynthesis , Glucosides/metabolism , Hyoscyamine/supply & distribution , Lactates/metabolism , Ligases/genetics , Ligases/metabolism , Models, Molecular , Nervous System Diseases/drug therapy , Oxidoreductases/genetics , Oxidoreductases/metabolism , Protein Engineering , Saccharomyces cerevisiae/genetics , Scopolamine/supply & distribution , Vacuoles/metabolism
20.
Nature ; 582(7813): 561-565, 2020 06.
Article in English | MEDLINE | ID: covidwho-164589

ABSTRACT

Reverse genetics has been an indispensable tool to gain insights into viral pathogenesis and vaccine development. The genomes of large RNA viruses, such as those from coronaviruses, are cumbersome to clone and manipulate in Escherichia coli owing to the size and occasional instability of the genome1-3. Therefore, an alternative rapid and robust reverse-genetics platform for RNA viruses would benefit the research community. Here we show the full functionality of a yeast-based synthetic genomics platform to genetically reconstruct diverse RNA viruses, including members of the Coronaviridae, Flaviviridae and Pneumoviridae families. Viral subgenomic fragments were generated using viral isolates, cloned viral DNA, clinical samples or synthetic DNA, and these fragments were then reassembled in one step in Saccharomyces cerevisiae using transformation-associated recombination cloning to maintain the genome as a yeast artificial chromosome. T7 RNA polymerase was then used to generate infectious RNA to rescue viable virus. Using this platform, we were able to engineer and generate chemically synthesized clones of the virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)4, which has caused the recent pandemic of coronavirus disease (COVID-19), in only a week after receipt of the synthetic DNA fragments. The technical advance that we describe here facilitates rapid responses to emerging viruses as it enables the real-time generation and functional characterization of evolving RNA virus variants during an outbreak.


Subject(s)
Betacoronavirus/genetics , Cloning, Molecular/methods , Coronavirus Infections/virology , Genome, Viral/genetics , Genomics/methods , Pneumonia, Viral/virology , Reverse Genetics/methods , Synthetic Biology/methods , Animals , COVID-19 , China/epidemiology , Chlorocebus aethiops , Chromosomes, Artificial, Yeast/metabolism , Coronavirus Infections/epidemiology , DNA-Directed RNA Polymerases/metabolism , Evolution, Molecular , Humans , Mutation , Pandemics/statistics & numerical data , Pneumonia, Viral/epidemiology , Respiratory Syncytial Viruses/genetics , SARS-CoV-2 , Saccharomyces cerevisiae/genetics , Vero Cells , Viral Proteins/metabolism , Zika Virus/genetics
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