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1.
J Med Chem ; 65(8): 6231-6249, 2022 04 28.
Article in English | MEDLINE | ID: covidwho-1867997

ABSTRACT

Enzymes involved in RNA capping of SARS-CoV-2 are essential for the stability of viral RNA, translation of mRNAs, and virus evasion from innate immunity, making them attractive targets for antiviral agents. In this work, we focused on the design and synthesis of nucleoside-derived inhibitors against the SARS-CoV-2 nsp14 (N7-guanine)-methyltransferase (N7-MTase) that catalyzes the transfer of the methyl group from the S-adenosyl-l-methionine (SAM) cofactor to the N7-guanosine cap. Seven compounds out of 39 SAM analogues showed remarkable double-digit nanomolar inhibitory activity against the N7-MTase nsp14. Molecular docking supported the structure-activity relationships of these inhibitors and a bisubstrate-based mechanism of action. The three most potent inhibitors significantly stabilized nsp14 (ΔTm ≈ 11 °C), and the best inhibitor demonstrated high selectivity for nsp14 over human RNA N7-MTase.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/drug therapy , COVID-19/virology , Exoribonucleases/antagonists & inhibitors , Exoribonucleases/chemistry , Humans , Methyltransferases , Molecular Docking Simulation , RNA, Viral/genetics , S-Adenosylmethionine , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Sulfonamides/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/chemistry
2.
Molecules ; 27(9)2022 Apr 23.
Article in English | MEDLINE | ID: covidwho-1855714

ABSTRACT

The COVID-19 pandemic is still affecting many people worldwide and causing a heavy burden to global health. To eliminate the disease, SARS-CoV-2, the virus responsible for the pandemic, can be targeted in several ways. One of them is to inhibit the 2'-O-methyltransferase (nsp16) enzyme that is crucial for effective translation of viral RNA and virus replication. For methylation of substrates, nsp16 utilizes S-adenosyl methionine (SAM). Binding of a small molecule in the protein site where SAM binds can disrupt the synthesis of viral proteins and, as a result, the replication of the virus. Here, we performed high-throughput docking into the SAM-binding site of nsp16 for almost 40 thousand structures, prepared for compounds from three libraries: Enamine Coronavirus Library, Enamine Nucleoside Mimetics Library, and Chemdiv Nucleoside Analogue Library. For the top scoring ligands, semi-empirical quantum-chemical calculations were performed, to better estimate protein-ligand binding enthalpy. Relying upon the calculated binding energies and predicted docking poses, we selected 21 compounds for experimental testing.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/drug therapy , Humans , Methyltransferases/chemistry , Molecular Docking Simulation , Pandemics , RNA, Viral/genetics , S-Adenosylmethionine , Viral Nonstructural Proteins/metabolism
3.
Molecules ; 27(7)2022 Mar 31.
Article in English | MEDLINE | ID: covidwho-1792596

ABSTRACT

As a continuation of our earlier work against SARS-CoV-2, seven FDA-approved drugs were designated as the best SARS-CoV-2 nsp16-nsp10 2'-o-methyltransferase (2'OMTase) inhibitors through 3009 compounds. The in silico inhibitory potential of the examined compounds against SARS-CoV-2 nsp16-nsp10 2'-o-methyltransferase (PDB ID: (6W4H) was conducted through a multi-step screening approach. At the beginning, molecular fingerprints experiment with SAM (S-Adenosylmethionine), the co-crystallized ligand of the targeted enzyme, unveiled the resemblance of 147 drugs. Then, a structural similarity experiment recommended 26 compounds. Therefore, the 26 compounds were docked against 2'OMTase to reveal the potential inhibitory effect of seven promising compounds (Protirelin, (1187), Calcium folinate (1913), Raltegravir (1995), Regadenoson (2176), Ertapenem (2396), Methylergometrine (2532), and Thiamine pyrophosphate hydrochloride (2612)). Out of the docked ligands, Ertapenem (2396) showed an ideal binding mode like that of the co-crystallized ligand (SAM). It occupied all sub-pockets of the active site and bound the crucial amino acids. Accordingly, some MD simulation experiments (RMSD, RMSF, Rg, SASA, and H-bonding) have been conducted for the 2'OMTase-Ertapenem complex over 100 ns. The performed MD experiments verified the correct binding mode of Ertapenem against 2'OMTase exhibiting low energy and optimal dynamics. Finally, MM-PBSA studies indicated that Ertapenem bonded advantageously to the targeted protein with a free energy value of -43 KJ/mol. Furthermore, the binding free energy analysis revealed the essential amino acids of 2'OMTase that served positively to the binding. The achieved results bring hope to find a treatment for COVID-19 via in vitro and in vivo studies for the pointed compounds.


Subject(s)
Methyltransferases , SARS-CoV-2 , Viral Nonstructural Proteins , Viral Regulatory and Accessory Proteins , Ertapenem/pharmacology , Ligands , Methyltransferases/antagonists & inhibitors , Molecular Docking Simulation , Molecular Dynamics Simulation , S-Adenosylmethionine/chemistry , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Regulatory and Accessory Proteins/antagonists & inhibitors
4.
Acc Chem Res ; 55(9): 1249-1261, 2022 05 03.
Article in English | MEDLINE | ID: covidwho-1788259

ABSTRACT

The central dogma of molecular biology hinges on messenger RNA (mRNA), which presents a blueprint of the genetic information encoded in the DNA and serves as a template for translation into proteins. In addition to its fundamental importance in basic research, this class of biomolecules has recently become the first approved Covid vaccine, underscoring its utility in medical applications.Eukaryotic mRNA is heavily processed, including the 5' cap as the primary hallmark. This 5' cap protects mRNA from degradation by exoribonucleases but also interacts specifically with several proteins and enzymes to ensure mRNA turnover and processing, like splicing, export from the nucleus to the cytoplasm, and initiation of translation. The absence of a 5' cap leads to a strong immune response, and the methylation status contributes to distinguishing self from non-self RNA.Non-natural modifications of the 5' cap provide an avenue to label mRNAs and make them accessible to analyses, which is important to study their cellular localization, trafficking, and binding partners. They bear potential to engineer mRNAs, e.g., more stable or immunogenic mRNAs that are still translated, by impacting select interactions in a distinct manner. The modification of the 5' cap itself is powerful as it can be applied to make long mRNAs (∼1000 nt, not directly accessible by solid-phase synthesis) by in vitro transcription.This Account describes our contribution to the field of chemo-enzymatic modification of mRNA at the 5' cap. Our approach relies on RNA methyltransferases (MTases) with promiscuous activity on analogues of their natural cosubstrate S-adenosyl-L-methionine (AdoMet). We will describe how RNA MTases in combination with non-natural cosubstrates provide access to site-specific modification of different positions of the 5' cap, namely, the N2 and N7 position of guanosine and the N6 position of adenosine as the transcription start nucleotide (TSN) and exemplify strategies to make long mRNAs with modified 5' caps.We will compare the chemical and enzymatic synthesis of the AdoMet analogues used for this purpose. We could overcome previous limitations in methionine adenosyltransferase (MAT) substrate scope by engineering variants (termed PC-MATs) with the ability to convert methionine analogues with benzylic and photocaging groups at the sulfonium ion.The final part of this Account will highlight applications of the modified mRNAs. Like in many chemo-enzymatic approaches, a versatile strategy is to install small functional groups enzymatically and use them as handles in subsequent bioorthogonal reactions. We showed fluorescent labeling of mRNAs via different types of click chemistry in vitro and in cells. In a second line of applications, we used the handles to make mRNAs amenable for analyses, most notably next-generation sequencing. In the case of extremely promiscuous enzymes, the direct installation of photo-cross-linking groups was successful also and provided a way to covalently bind protein-interaction partners. Finally, the non-natural modifications of mRNAs can also modulate the properties of mRNAs. Propargylation of Am as the transcription start nucleotide at its N6 position maintained the translation of mRNAs but increased their immunogenicity. The installation of photocaging groups provides a way to revert these effects and control interactions by light.


Subject(s)
RNA, Messenger , S-Adenosylmethionine , COVID-19 Vaccines , Humans , Methionine , Methyltransferases/genetics , Methyltransferases/metabolism , Nucleotides , RNA , RNA, Messenger/metabolism , S-Adenosylmethionine/chemistry
5.
Nature ; 602(7896): 343-348, 2022 02.
Article in English | MEDLINE | ID: covidwho-1671588

ABSTRACT

Carbapenems are antibiotics of last resort in the clinic. Owing to their potency and broad-spectrum activity, they are an important part of the antibiotic arsenal. The vital role of carbapenems is exemplified by the approval acquired by Merck from the US Food and Drug Administration (FDA) for the use of an imipenem combination therapy to treat the increased levels of hospital-acquired and ventilator-associated bacterial pneumonia that have occurred during the COVID-19 pandemic1. The C6 hydroxyethyl side chain distinguishes the clinically used carbapenems from the other classes of ß-lactam antibiotics and is responsible for their low susceptibility to inactivation by occluding water from the ß-lactamase active site2. The construction of the C6 hydroxyethyl side chain is mediated by cobalamin- or B12-dependent radical S-adenosylmethionine (SAM) enzymes3. These radical SAM methylases (RSMTs) assemble the alkyl backbone by sequential methylation reactions, and thereby underlie the therapeutic usefulness of clinically used carbapenems. Here we present X-ray crystal structures of TokK, a B12-dependent RSMT that catalyses three-sequential methylations during the biosynthesis of asparenomycin A. These structures, which contain the two metallocofactors of the enzyme and were determined in the presence and absence of a carbapenam substrate, provide a visualization of a B12-dependent RSMT that uses the radical mechanism that is shared by most of these enzymes. The structures provide insight into the stereochemistry of initial C6 methylation and suggest that substrate positioning governs the rate of each methylation event.


Subject(s)
Carbapenems/biosynthesis , Methyltransferases/chemistry , Methyltransferases/metabolism , S-Adenosylmethionine/metabolism , Streptomyces/enzymology , Thienamycins/biosynthesis , Vitamin B 12/metabolism , Binding Sites , Biocatalysis , Coenzymes/metabolism , Crystallography, X-Ray , Kinetics , Methylation , Models, Molecular , Protein Binding , Protein Domains , Streptomyces/metabolism , beta-Lactamase Inhibitors/metabolism , beta-Lactamases/chemistry , beta-Lactamases/metabolism
6.
Dis Markers ; 2021: 7686374, 2021.
Article in English | MEDLINE | ID: covidwho-1595046

ABSTRACT

OBJECTIVE: S-Adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are indicators of global transmethylation and may play an important role as markers of severity of COVID-19. METHODS: The levels of plasma SAM and SAH were determined in patients admitted with COVID-19 (n = 56, mean age = 61). Lung injury was identified by computed tomography (CT) in accordance with the CT0-4 classification. RESULTS: SAM was found to be a potential marker of lung damage risk in COVID-19 patients (SAM > 80 nM; CT3,4 vs. CT 0-2: relative ratio (RR) was 3.0; p = 0.0029). SAM/SAH > 6.0 was also found to be a marker of lung injury (CT2-4 vs. CT0,1: RR = 3.47, p = 0.0004). There was a negative association between SAM and glutathione level (ρ = -0.343, p = 0.011). Interleukin-6 (IL-6) levels were associated with SAM (ρ = 0.44, p = 0.01) and SAH (ρ = 0.534, p = 0.001) levels. CONCLUSIONS: A high SAM level and high methylation index are associated with the risk of lung injury in patients with COVID-19. The association of SAM with IL-6 and glutathione indicates an important role of transmethylation in the development of cytokine imbalance and oxidative stress in patients with COVID-19.


Subject(s)
COVID-19/complications , Lung Injury/blood , S-Adenosylhomocysteine/blood , S-Adenosylmethionine/blood , SARS-CoV-2 , Adult , Aged , Aged, 80 and over , Atherosclerosis/epidemiology , Biomarkers , COVID-19/epidemiology , Comorbidity , Diabetes Mellitus/epidemiology , Female , Glutathione/blood , Humans , Hypertension/epidemiology , Interleukin-6/blood , Lung Injury/diagnostic imaging , Lung Injury/etiology , Male , Methylation , Middle Aged , Military Personnel , Risk , Tomography, X-Ray Computed , Young Adult
7.
Molecules ; 26(20)2021 Oct 12.
Article in English | MEDLINE | ID: covidwho-1518621

ABSTRACT

In continuation of our previous effort, different in silico selection methods were applied to 310 naturally isolated metabolites that exhibited antiviral potentialities before. The applied selection methods aimed to pick the most relevant inhibitor of SARS-CoV-2 nsp10. At first, a structural similarity study against the co-crystallized ligand, S-Adenosyl Methionine (SAM), of SARS-CoV-2 nonstructural protein (nsp10) (PDB ID: 6W4H) was carried out. The similarity analysis culled 30 candidates. Secondly, a fingerprint study against SAM preferred compounds 44, 48, 85, 102, 105, 182, 220, 221, 282, 284, 285, 301, and 302. The docking studies picked 48, 182, 220, 221, and 284. While the ADMET analysis expected the likeness of the five candidates to be drugs, the toxicity study preferred compounds 48 and 182. Finally, a density-functional theory (DFT) study suggested vidarabine (182) to be the most relevant SARS-Cov-2 nsp10 inhibitor.


Subject(s)
Antiviral Agents/chemistry , Biological Products/chemistry , SARS-CoV-2/metabolism , Viral Regulatory and Accessory Proteins/antagonists & inhibitors , Antiviral Agents/metabolism , Antiviral Agents/therapeutic use , Binding Sites , Biological Products/metabolism , Biological Products/therapeutic use , COVID-19/drug therapy , COVID-19/pathology , Density Functional Theory , Humans , Ligands , Molecular Docking Simulation , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , SARS-CoV-2/isolation & purification , Small Molecule Libraries/chemistry , Small Molecule Libraries/metabolism , Small Molecule Libraries/therapeutic use , Vidarabine/chemistry , Vidarabine/metabolism , Vidarabine/therapeutic use , Viral Regulatory and Accessory Proteins/metabolism
8.
Molecules ; 26(20)2021 Oct 12.
Article in English | MEDLINE | ID: covidwho-1463775

ABSTRACT

In continuation of our previous effort, different in silico selection methods were applied to 310 naturally isolated metabolites that exhibited antiviral potentialities before. The applied selection methods aimed to pick the most relevant inhibitor of SARS-CoV-2 nsp10. At first, a structural similarity study against the co-crystallized ligand, S-Adenosyl Methionine (SAM), of SARS-CoV-2 nonstructural protein (nsp10) (PDB ID: 6W4H) was carried out. The similarity analysis culled 30 candidates. Secondly, a fingerprint study against SAM preferred compounds 44, 48, 85, 102, 105, 182, 220, 221, 282, 284, 285, 301, and 302. The docking studies picked 48, 182, 220, 221, and 284. While the ADMET analysis expected the likeness of the five candidates to be drugs, the toxicity study preferred compounds 48 and 182. Finally, a density-functional theory (DFT) study suggested vidarabine (182) to be the most relevant SARS-Cov-2 nsp10 inhibitor.


Subject(s)
Antiviral Agents/chemistry , Biological Products/chemistry , SARS-CoV-2/metabolism , Viral Regulatory and Accessory Proteins/antagonists & inhibitors , Antiviral Agents/metabolism , Antiviral Agents/therapeutic use , Binding Sites , Biological Products/metabolism , Biological Products/therapeutic use , COVID-19/drug therapy , COVID-19/pathology , Density Functional Theory , Humans , Ligands , Molecular Docking Simulation , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , SARS-CoV-2/isolation & purification , Small Molecule Libraries/chemistry , Small Molecule Libraries/metabolism , Small Molecule Libraries/therapeutic use , Vidarabine/chemistry , Vidarabine/metabolism , Vidarabine/therapeutic use , Viral Regulatory and Accessory Proteins/metabolism
9.
Sci Signal ; 14(689)2021 06 29.
Article in English | MEDLINE | ID: covidwho-1406596

ABSTRACT

Capping of viral messenger RNAs is essential for efficient translation, for virus replication, and for preventing detection by the host cell innate response system. The SARS-CoV-2 genome encodes the 2'-O-methyltransferase nsp16, which, when bound to the coactivator nsp10, uses S-adenosylmethionine (SAM) as a donor to transfer a methyl group to the first ribonucleotide of the mRNA in the final step of viral mRNA capping. Here, we provide biochemical and structural evidence that this reaction requires divalent cations, preferably Mn2+, and a coronavirus-specific four-residue insert. We determined the x-ray structures of the SARS-CoV-2 2'-O-methyltransferase (the nsp16-nsp10 heterodimer) in complex with its reaction substrates, products, and divalent metal cations. These structural snapshots revealed that metal ions and the insert stabilize interactions between the capped RNA and nsp16, resulting in the precise alignment of the ribonucleotides in the active site. Comparison of available structures of 2'-O-methyltransferases with capped RNAs from different organisms revealed that the four-residue insert unique to coronavirus nsp16 alters the backbone conformation of the capped RNA in the binding groove, thereby promoting catalysis. This insert is highly conserved across coronaviruses, and its absence in mammalian methyltransferases makes this region a promising site for structure-guided drug design of selective coronavirus inhibitors.


Subject(s)
COVID-19/virology , RNA Caps/metabolism , RNA, Viral/metabolism , SARS-CoV-2/metabolism , Viral Nonstructural Proteins/metabolism , Amino Acid Sequence , Catalytic Domain , Crystallography, X-Ray , Humans , Manganese/metabolism , Methylation , Methyltransferases/chemistry , Methyltransferases/genetics , Methyltransferases/metabolism , Models, Molecular , Nucleic Acid Conformation , RNA Caps/chemistry , RNA Caps/genetics , RNA Stability , RNA, Messenger/chemistry , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Viral/chemistry , RNA, Viral/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , SARS-CoV-2/genetics , Signal Transduction , Substrate Specificity , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/genetics
10.
Angew Chem Int Ed Engl ; 60(24): 13280-13286, 2021 06 07.
Article in English | MEDLINE | ID: covidwho-1384109

ABSTRACT

Eukaryotic mRNAs are emerging modalities for protein replacement therapy and vaccination. Their 5' cap is important for mRNA translation and immune response and can be naturally methylated at different positions by S-adenosyl-l-methionine (AdoMet)-dependent methyltransferases (MTases). We report on the cosubstrate scope of the MTase CAPAM responsible for methylation at the N6 -position of adenosine start nucleotides using synthetic AdoMet analogs. The chemo-enzymatic propargylation enabled production of site-specifically modified reporter-mRNAs. These cap-propargylated mRNAs were efficiently translated and showed ≈3-fold increased immune response in human cells. The same effects were observed when the receptor binding domain (RBD) of SARS-CoV-2-a currently tested epitope for mRNA vaccination-was used. Site-specific chemo-enzymatic modification of eukaryotic mRNA may thus be a suitable strategy to modulate translation and immune response of mRNAs for future therapeutic applications.


Subject(s)
RNA Caps/immunology , RNA, Messenger/immunology , COVID-19/pathology , COVID-19/virology , Chromatography, High Pressure Liquid , Genes, Reporter , HEK293 Cells , Humans , Mass Spectrometry , Methylation , Methyltransferases/metabolism , Protein Biosynthesis , Protein Domains/genetics , Protein Domains/immunology , RNA Caps/analysis , RNA Caps/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/immunology , S-Adenosylmethionine/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
11.
Int J Mol Sci ; 21(19)2020 Oct 06.
Article in English | MEDLINE | ID: covidwho-1298151

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), causing Coronavirus Disease 19 (COVID-19), emerged at the end of 2019 and quickly spread to cause a global pandemic with severe socio-economic consequences. The early sequencing of its RNA genome revealed its high similarity to SARS, likely to have originated from bats. The SARS-CoV-2 non-structural protein 10 (nsp10) displays high sequence similarity with its SARS homologue, which binds to and stimulates the 3'-to-5' exoribonuclease and the 2'-O-methlytransferase activities of nsps 14 and 16, respectively. Here, we report the biophysical characterization and 1.6 Å resolution structure of the unbound form of nsp10 from SARS-CoV-2 and compare it to the structures of its SARS homologue and the complex-bound form with nsp16 from SARS-CoV-2. The crystal structure and solution behaviour of nsp10 will not only form the basis for understanding the role of SARS-CoV-2 nsp10 as a central player of the viral RNA capping apparatus, but will also serve as a basis for the development of inhibitors of nsp10, interfering with crucial functions of the replication-transcription complex and virus replication.


Subject(s)
Molecular Dynamics Simulation , Viral Regulatory and Accessory Proteins/chemistry , Binding Sites , Crystallography, X-Ray , Protein Binding , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , Sequence Homology , Viral Regulatory and Accessory Proteins/metabolism , Zinc Fingers
12.
Nat Commun ; 12(1): 3287, 2021 06 02.
Article in English | MEDLINE | ID: covidwho-1253936

ABSTRACT

The SARS-CoV-2 nsp16/nsp10 enzyme complex modifies the 2'-OH of the first transcribed nucleotide of the viral mRNA by covalently attaching a methyl group to it. The 2'-O methylation of the first nucleotide converts the status of mRNA cap from Cap-0 to Cap-1, and thus, helps the virus evade immune surveillance in host cells. Here, we report two structures of nsp16/nsp10 representing pre- and post-release states of the RNA product (Cap-1). We observe overall widening of the enzyme upon product formation, and an inward twisting motion in the substrate binding region upon product release. These conformational changes reset the enzyme for the next round of catalysis. The structures also identify a unique binding mode and the importance of a divalent metal ion for 2'-O methylation. We also describe underlying structural basis for the perturbed enzymatic activity of a clinical variant of SARS-CoV-2, and a previous SARS-CoV outbreak strain.


Subject(s)
Magnesium/chemistry , RNA Caps/metabolism , RNA, Viral/metabolism , SARS-CoV-2/genetics , Viral Nonstructural Proteins/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Amino Acid Sequence , Binding Sites , Biocatalysis , Cloning, Molecular , Crystallography, X-Ray , Escherichia coli/genetics , Escherichia coli/metabolism , Gene Expression Regulation, Viral , Humans , Magnesium/metabolism , Methylation , Methyltransferases , Models, Molecular , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , RNA Caps/chemistry , RNA Caps/genetics , RNA, Viral/chemistry , RNA, Viral/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , SARS-CoV-2/enzymology , SARS-CoV-2/ultrastructure , Sequence Alignment , Sequence Homology, Amino Acid , Substrate Specificity , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/genetics , Viral Regulatory and Accessory Proteins/chemistry , Viral Regulatory and Accessory Proteins/genetics
13.
Nucleic Acids Res ; 49(W1): W207-W215, 2021 07 02.
Article in English | MEDLINE | ID: covidwho-1238218

ABSTRACT

Transcriptome profiling is essential for gene regulation studies in development and disease. Current web-based tools enable functional characterization of transcriptome data, but most are restricted to applying gene-list-based methods to single datasets, inefficient in leveraging up-to-date and species-specific information, and limited in their visualization options. Additionally, there is no systematic way to explore data stored in the largest transcriptome repository, NCBI GEO. To fill these gaps, we have developed eVITTA (easy Visualization and Inference Toolbox for Transcriptome Analysis; https://tau.cmmt.ubc.ca/eVITTA/). eVITTA provides modules for analysis and exploration of studies published in NCBI GEO (easyGEO), detailed molecular- and systems-level functional profiling (easyGSEA), and customizable comparisons among experimental groups (easyVizR). We tested eVITTA on transcriptomes of SARS-CoV-2 infected human nasopharyngeal swab samples, and identified a downregulation of olfactory signal transducers, in line with the clinical presentation of anosmia in COVID-19 patients. We also analyzed transcriptomes of Caenorhabditis elegans worms with disrupted S-adenosylmethionine metabolism, confirming activation of innate immune responses and feedback induction of one-carbon cycle genes. Collectively, eVITTA streamlines complex computational workflows into an accessible interface, thus filling the gap of an end-to-end platform capable of capturing both broad and granular changes in human and model organism transcriptomes.


Subject(s)
Data Visualization , Databases, Genetic , Gene Expression Profiling/methods , Internet , Transcriptome/genetics , Animals , COVID-19/genetics , COVID-19/virology , Caenorhabditis elegans/genetics , Caenorhabditis elegans/metabolism , Humans , Immunity, Innate , Nasopharynx/virology , S-Adenosylmethionine/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Species Specificity , Workflow
14.
Proc Natl Acad Sci U S A ; 118(21)2021 05 25.
Article in English | MEDLINE | ID: covidwho-1223143

ABSTRACT

The genome of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronavirus has a capping modification at the 5'-untranslated region (UTR) to prevent its degradation by host nucleases. These modifications are performed by the Nsp10/14 and Nsp10/16 heterodimers using S-adenosylmethionine as the methyl donor. Nsp10/16 heterodimer is responsible for the methylation at the ribose 2'-O position of the first nucleotide. To investigate the conformational changes of the complex during 2'-O methyltransferase activity, we used a fixed-target serial synchrotron crystallography method at room temperature. We determined crystal structures of Nsp10/16 with substrates and products that revealed the states before and after methylation, occurring within the crystals during the experiments. Here we report the crystal structure of Nsp10/16 in complex with Cap-1 analog (m7GpppAm2'-O). Inhibition of Nsp16 activity may reduce viral proliferation, making this protein an attractive drug target.


Subject(s)
RNA Caps/metabolism , RNA, Messenger/metabolism , RNA, Viral/metabolism , SARS-CoV-2/chemistry , Crystallography , Methylation , Methyltransferases/chemistry , Methyltransferases/metabolism , Multiprotein Complexes/chemistry , Multiprotein Complexes/metabolism , RNA Cap Analogs/chemistry , RNA Cap Analogs/metabolism , RNA Caps/chemistry , RNA, Messenger/chemistry , RNA, Viral/chemistry , S-Adenosylhomocysteine/chemistry , S-Adenosylhomocysteine/metabolism , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/metabolism , Synchrotrons , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/metabolism , Viral Regulatory and Accessory Proteins/chemistry , Viral Regulatory and Accessory Proteins/metabolism
15.
J Virol ; 94(16)2020 07 30.
Article in English | MEDLINE | ID: covidwho-1214962

ABSTRACT

The 5' cap methylation of viral RNA plays important roles in RNA stability, efficient translation, and immune evasion. Thus, RNA cap methylation is an attractive target for antiviral discovery and development of new live attenuated vaccines. For coronaviruses, RNA cap structure is first methylated at the guanine-N-7 (G-N-7) position by nonstructural protein 14 (nsp14), which facilitates and precedes the subsequent ribose 2'-O methylation by the nsp16-nsp10 complex. Using porcine epidemic diarrhea virus (PEDV), an Alphacoronavirus, as a model, we showed that G-N-7 methyltransferase (G-N-7 MTase) of PEDV nsp14 methylated RNA substrates in a sequence-unspecific manner. PEDV nsp14 can efficiently methylate RNA substrates with various lengths in both neutral and alkaline pH environments and can methylate cap analogs (GpppA and GpppG) and single-nucleotide GTP but not ATP, CTP, or UTP. Mutations to the S-adenosyl-l-methionine (SAM) binding motif in the nsp14 abolished the G-N-7 MTase activity and were lethal to PEDV. However, recombinant rPEDV-D350A with a single mutation (D350A) in nsp14, which retained 29.0% of G-N-7 MTase activity, was viable. Recombinant rPEDV-D350A formed a significantly smaller plaque and had significant defects in viral protein synthesis and viral replication in Vero CCL-81 cells and intestinal porcine epithelial cells (IPEC-DQ). Notably, rPEDV-D350A induced significantly higher expression of both type I and III interferons in IPEC-DQ cells than the parental rPEDV. Collectively, our results demonstrate that G-N-7 MTase activity of PEDV modulates viral replication, gene expression, and innate immune responses.IMPORTANCE Coronaviruses (CoVs) include a wide range of important human and animal pathogens. Examples of human CoVs include severe acute respiratory syndrome coronavirus (SARS-CoV-1), Middle East respiratory syndrome coronavirus (MERS-CoV), and the most recently emerged SARS-CoV-2. Examples of pig CoVs include porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), and swine enteric alphacoronavirus (SeACoV). There are no vaccines or antiviral drugs for most of these viruses. All known CoVs encode a bifunctional nsp14 protein which possesses ExoN and guanine-N-7 methyltransferase (G-N-7 MTase) activities, responsible for replication fidelity and RNA cap G-N-7 methylation, respectively. Here, we biochemically characterized G-N-7 MTase of PEDV nsp14 and found that G-N-7 MTase-deficient PEDV was defective in replication and induced greater responses of type I and III interferons. These findings highlight that CoV G-N-7 MTase may be a novel target for rational design of live attenuated vaccines and antiviral drugs.


Subject(s)
Exoribonucleases/metabolism , Interferon Type I/biosynthesis , Interferons/biosynthesis , Porcine epidemic diarrhea virus/physiology , RNA Caps/metabolism , Viral Nonstructural Proteins/metabolism , Animals , Binding Sites , Cell Line , Chlorocebus aethiops , Exoribonucleases/genetics , Gene Expression , Guanine/metabolism , Immunity, Innate , Methylation , Mutation , Porcine epidemic diarrhea virus/enzymology , Porcine epidemic diarrhea virus/genetics , Porcine epidemic diarrhea virus/pathogenicity , RNA, Viral/metabolism , S-Adenosylmethionine/metabolism , Swine , Vero Cells , Viral Nonstructural Proteins/genetics , Virus Replication
16.
Biomater Sci ; 9(6): 1961-1973, 2021 Mar 21.
Article in English | MEDLINE | ID: covidwho-1065971

ABSTRACT

Methionine (Met), an essential amino acid in the human body, possesses versatile features based on its chemical modification, cell metabolism and metabolic derivatives. Benefitting from its multifunctional properties, Met holds immense potential for biomedical applications. In this review, we systematically summarize the recent progress in Met-based strategies for biomedical applications. First, given the unique structural characteristics of Met, two chemical modification methods are briefly introduced. Subsequently, due to the disordered metabolic state of tumor cells, applications of Met in cancer treatment and diagnosis are summarized in detail. Furthermore, the efficacy of S-adenosylmethionine (SAM), as the most important metabolic derivative of Met, for treating liver diseases is mentioned. Finally, we analyze the current challenges and development trends of Met in the biomedical field, and suggest that Met-restriction therapy might be a promising approach to treat COVID-19.


Subject(s)
Methionine/metabolism , Neoplasms/metabolism , COVID-19/drug therapy , COVID-19/pathology , COVID-19/virology , Cell Proliferation/drug effects , Docetaxel/chemistry , Docetaxel/pharmacology , Humans , Liver Diseases/diet therapy , Liver Diseases/pathology , Methionine/chemistry , Methionine/deficiency , Nanoparticles/chemistry , Neoplasms/drug therapy , Neoplasms/pathology , S-Adenosylmethionine/therapeutic use , SARS-CoV-2/isolation & purification
17.
FEBS J ; 288(12): 3715-3726, 2021 06.
Article in English | MEDLINE | ID: covidwho-923390

ABSTRACT

In response to viral infections, the innate immune system rapidly activates expression of several interferon-stimulated genes (ISGs), whose protein and metabolic products are believed to directly interfere with the viral life cycle. Here, we argue that biochemical reactions performed by two specific protein products of ISGs modulate central carbon metabolism to support a broad-spectrum antiviral response. We demonstrate that the metabolites generated by metalloenzymes nitric oxide synthase and the radical S-adenosylmethionine (SAM) enzyme RSAD2 inhibit the activity of the housekeeping and glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). We discuss that this inhibition is likely to stimulate a range of metabolic and signalling processes to support a broad-spectrum immune response. Based on these analyses, we propose that inhibiting GAPDH in individuals with deteriorated cellular innate immune response like elderly might help in treating viral diseases such as COVID-19.


Subject(s)
Antiviral Agents/metabolism , Carbon/metabolism , Interferons/metabolism , Proteins/metabolism , S-Adenosylmethionine/metabolism , Antiviral Agents/pharmacology , COVID-19/prevention & control , COVID-19/virology , Cells, Cultured , Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating)/metabolism , HEK293 Cells , Humans , Immunity, Innate/drug effects , Induced Pluripotent Stem Cells/metabolism , Macrophages/metabolism , Models, Biological , Oxidoreductases Acting on CH-CH Group Donors , Proteins/genetics , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Virus Replication/drug effects
18.
Sci Signal ; 13(651)2020 09 29.
Article in English | MEDLINE | ID: covidwho-808027

ABSTRACT

There are currently no antiviral therapies specific for SARS-CoV-2, the virus responsible for the global pandemic disease COVID-19. To facilitate structure-based drug design, we conducted an x-ray crystallographic study of the SARS-CoV-2 nsp16-nsp10 2'-O-methyltransferase complex, which methylates Cap-0 viral mRNAs to improve viral protein translation and to avoid host immune detection. We determined the structures for nsp16-nsp10 heterodimers bound to the methyl donor S-adenosylmethionine (SAM), the reaction product S-adenosylhomocysteine (SAH), or the SAH analog sinefungin (SFG). We also solved structures for nsp16-nsp10 in complex with the methylated Cap-0 analog m7GpppA and either SAM or SAH. Comparative analyses between these structures and published structures for nsp16 from other betacoronaviruses revealed flexible loops in open and closed conformations at the m7GpppA-binding pocket. Bound sulfates in several of the structures suggested the location of the ribonucleic acid backbone phosphates in the ribonucleotide-binding groove. Additional nucleotide-binding sites were found on the face of the protein opposite the active site. These various sites and the conserved dimer interface could be exploited for the development of antiviral inhibitors.


Subject(s)
Betacoronavirus/enzymology , Coronavirus Infections/drug therapy , Methyltransferases/chemistry , Pneumonia, Viral/drug therapy , Viral Nonstructural Proteins/chemistry , Adenosine/analogs & derivatives , Adenosine/metabolism , Adenosine/pharmacology , Betacoronavirus/drug effects , Binding Sites , COVID-19 , Catalytic Domain , Crystallography, X-Ray , Dimerization , Genes, Viral/genetics , Humans , Methylation , Methyltransferases/antagonists & inhibitors , Models, Molecular , Open Reading Frames/genetics , Pandemics , Protein Binding , Protein Conformation , RNA Cap Analogs/metabolism , RNA Processing, Post-Transcriptional , RNA, Viral/metabolism , S-Adenosylhomocysteine/metabolism , S-Adenosylmethionine/metabolism , SARS-CoV-2 , Structure-Activity Relationship , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism
20.
Nat Commun ; 11(1): 3718, 2020 07 24.
Article in English | MEDLINE | ID: covidwho-680541

ABSTRACT

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19 illness, has caused millions of infections worldwide. In SARS coronaviruses, the non-structural protein 16 (nsp16), in conjunction with nsp10, methylates the 5'-end of virally encoded mRNAs to mimic cellular mRNAs, thus protecting the virus from host innate immune restriction. We report here the high-resolution structure of a ternary complex of SARS-CoV-2 nsp16 and nsp10 in the presence of cognate RNA substrate analogue and methyl donor, S-adenosyl methionine (SAM). The nsp16/nsp10 heterodimer is captured in the act of 2'-O methylation of the ribose sugar of the first nucleotide of SARS-CoV-2 mRNA. We observe large conformational changes associated with substrate binding as the enzyme transitions from a binary to a ternary state. This induced fit model provides mechanistic insights into the 2'-O methylation of the viral mRNA cap. We also discover a distant (25 Å) ligand-binding site unique to SARS-CoV-2, which can alternatively be targeted, in addition to RNA cap and SAM pockets, for antiviral development.


Subject(s)
Methyltransferases/chemistry , RNA Caps/metabolism , Viral Nonstructural Proteins/chemistry , Viral Regulatory and Accessory Proteins/chemistry , Betacoronavirus , COVID-19 , Coronavirus Infections/virology , Humans , Methyltransferases/metabolism , Models, Chemical , Models, Molecular , Pandemics , Pneumonia, Viral/virology , RNA, Viral/metabolism , S-Adenosylmethionine/metabolism , SARS-CoV-2 , Viral Nonstructural Proteins/metabolism , Viral Regulatory and Accessory Proteins/metabolism , X-Ray Diffraction
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