scholarly journals Severe acute respiratory syndrome coronavirus Orf3a protein interacts with caveolin

2007 ◽  
Vol 88 (11) ◽  
pp. 3067-3077 ◽  
Author(s):  
Kartika Padhan ◽  
Charu Tanwar ◽  
Amjad Hussain ◽  
Pui Yan Hui ◽  
Man Yan Lee ◽  
...  
Keyword(s):  
Life Cycle ◽  
Severe Acute Respiratory Syndrome ◽  
Binding Sites ◽  
Viral Life Cycle ◽  
Membrane Topology ◽  
Reading Frame ◽  
Caveolin 1 ◽  
Golgi Region ◽  
Genetic Techniques

The orf3a (also called X1 or U274) gene is the largest unique open reading frame in the severe acute respiratory syndrome coronavirus genome and has been proposed to encode a protein with three transmembrane domains and a large cytoplasmic domain. Recent work has suggested that the 3a protein may play a structural role in the viral life cycle, although the mechanisms for this remain uncharacterized. Here, the expression of the 3a protein in various in vitro systems is shown, it has been localized to the Golgi region and its membrane topology in transfected cells has been confirmed. Three potential caveolin-1-binding sites were reported to be present in the 3a protein. By using various biochemical, biophysical and genetic techniques, interaction of the 3a protein with caveolin-1 is demonstrated. Any one of the potential sites in the 3a protein was sufficient for this interaction. These results are discussed with respect to the possible roles of the 3a protein in the viral life cycle.

Molecular Docking of Azithromycin, Ritonavir, Lopinavir, Oseltamivir, Ivermectin and Heparin Interacting with Coronavirus Disease 2019 Main and Severe Acute Respiratory Syndrome Coronavirus-2 3C-Like Proteases

2021 ◽  
Vol 21 (4) ◽  
pp. 2075-2089
Author(s):  
Tiago da Silva Arouche ◽  
Anderson Yuri Martins ◽  
Teodorico de Castro Ramalho ◽  
Raul Nunes Carvalho Júnior ◽  
Fabio Luiz Paranhos Costa ◽  
...  
Keyword(s):  
Life Cycle ◽  
Viral Life Cycle ◽  
Stable Complex ◽  
Viral Agent ◽  
Main Protease ◽  
Wide Range ◽  
Approved Drugs ◽  
Pharmacologically Active ◽  
3Cl Protease

In the current pandemic situation raised due to COVID-19, drug reuse is emerging as the first line of treatment. The viral agent that causes this highly contagious disease and the acute respiratory syndrome coronavirus (SARS-CoV) share high nucleotide similarity. Therefore, it is structurally expected that many existing viral targets are similar to the first SARS-CoV, probably being inhibited by the same compounds. Here, we selected two viral proteins based on their vital role in the viral life cycle: Structure of the main protease SARS-CoV-2 and the structural base of the SARS-CoV-2 protease 3CL, both supporting the entry of the virus into the human host. The approved drugs used were azithromycin, ritonavir, lopinavir, oseltamivir, ivermectin and heparin, which are emerging as promising agents in the fight against COVID-19. Our hypothesis behind molecular coupling studies is to determine the binding affinities of these drugs and to identify the main amino acid residues that play a fundamental role in their mechanism of action. Additional studies on a wide range of FDA-approved drugs, including a few more protein targets, molecular dynamics studies, in vitro and biological in vivo evaluation are needed to identify combination therapy targeted at various stages of the viral life cycle. In our experiment in silico, based mainly on the molecular coupling approach, we investigated six different types of pharmacologically active drugs, aiming at their potential application alone or in combination with the reuse of drugs. The ligands showed stable conformations when analyzing the affinity energy in both proteases: ivermectin forming a stable complex with the two proteases with values −8.727 kcal/mol for Main Protease and −9.784 kcal/mol for protease 3CL, Heparin with values of −7.647 kcal/mol for the Main protease and −7.737 kcal/mol for the 3CL protease. Both conform to the catalytic site of the proteases. Our studies can provide an insight into the possible interactions between ligands and receptors, through better conformation. The ligands ivermectin, heparin and ritonavir showed stable conformations. Our in-silica docking data shows that the drugs we have identified can bind to the binding compartment of both proteases, this strongly supports our hypothesis that the development of a single antiviral agent targeting Main protease, or 3CL protease, or an agent used in combination with other potential therapies, it could provide an effective line of defense against diseases associated with coronaviruses.

Interspersion of an unusual GCN4 activation site with a complex transcriptional repression site in Ty2 elements of Saccharomyces cerevisiae

1993 ◽  
Vol 13 (4) ◽  
pp. 2091-2103
Author(s):  
S Türkel ◽  
P J Farabaugh
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Transcriptional Repression ◽  
Physiological Control ◽  
Reading Frame ◽  
Negative Region ◽  
Activation Site

Transcription of the Ty2-917 retrotransposon of Saccharomyces cerevisiae is modulated by a complex set of positive and negative elements, including a negative region located within the first open reading frame, TYA2. The negative region includes three downstream repression sites (DRSI, DRSII, and DRSIII). In addition, the negative region includes at least two downstream activation sites (DASs). This paper concerns the characterization of DASI. A 36-bp DASI oligonucleotide acts as an autonomous transcriptional activation site and includes two sequence elements which are both required for activation. We show that these sites bind in vitro the transcriptional activation protein GCN4 and that their activity in vivo responds to the level of GCN4 in the cell. We have termed the two sites GCN4 binding sites (GBS1 and GBS2). GBS1 is a high-affinity GCN4 binding site (dissociation constant, approximately 25 nM at 30 degrees C), binding GCN4 with about the affinity of a consensus UASGCN4, this though GBS1 includes two differences from the right half of the palindromic consensus site. GBS2 is more diverged from the consensus and binds GCN4 with about 20-fold-lower affinity. Nucleotides 13 to 36 of DASI overlap DRSII. Since DRSII is a transcriptional repression site, we tested whether DASI includes repression elements. We identify two sites flanking GBS2, both of which repress transcription activated by the consensus GCN4-specific upstream activation site (UASGCN4). One of these is repeated in the 12 bp immediately adjacent to DASI. Thus, in a 48-bp region of Ty2-917 are interspersed two positive and three negative transcriptional regulators. The net effect of the region must depend on the interaction of the proteins bound at these sites, which may include their competing for binding sites, and on the physiological control of the activity of these proteins.

The epidermal growth factor receptor is a relevant host factor in the early stages of Zika virus life cycle in vitro

2021 ◽  
Author(s):  
Catarina Sabino ◽  
Daniela Bender ◽  
Marie-Luise Herrlein ◽  
Eberhard Hildt
Keyword(s):  
Life Cycle ◽  
Zika Virus ◽  
A549 Cells ◽  
Growth Factor Receptor ◽  
Viral Life Cycle ◽  
Infection Process ◽  
Zikv Infection ◽  
Early Stages ◽  
Egfr Expression

Zika virus (ZIKV) is a flavivirus well-known for the epidemic in the Americas in 2015-2016, where microcephaly in newborns and other neurological complications were connected to ZIKV infection. Many aspects of the viral life cycle, including binding and entry into the host cell, are still enigmatic. Based on the observation that CHO cells lack the expression of EGFR and are not permissive for various ZIKV strains, the relevance of EGFR for the viral life cycle was analyzed. Infection of A549 cells by ZIKV leads to a rapid internalization of EGFR that colocalizes with the endosomal marker EEA1. Moreover, the infection by different ZIKV strains is associated with an activation of EGFR and subsequent activation of the MAPK/ERK signaling cascade. However, treatment of the cells with MβCD, which on the one hand leads to an activation of EGFR but on the other hand prevents EGFR internalization, impairs ZIKV infection. Specific inhibition of EGFR or of the RAS-RAF-MEK-ERK signal transduction cascade hinders ZIKV infection by inhibition of ZIKV entry. In accordance to this, knockout of EGFR expression impedes ZIKV entry. In case of an already established infection, inhibition of EGFR or of downstream signaling does not affect viral replication. Taken together, these data demonstrate the relevance of EGFR in the early stages of ZIKV infection and identify EGFR as a target for antiviral strategies. Importance These data deepen the knowledge about the ZIKV infection process and demonstrate the relevance of EGFR for ZIKV entry. In light of the fact that a variety of specific and efficient inhibitors of EGFR and of EGFR-dependent signaling were developed and licensed, repurposing of these substances could be a helpful tool to prevent the spreading of ZIKV infection in an epidemic outbreak.

scholarly journals The Open Reading Frame 3a Protein of Severe Acute Respiratory Syndrome-Associated Coronavirus Promotes Membrane Rearrangement and Cell Death

2009 ◽  
Vol 84 (2) ◽  
pp. 1097-1109 ◽  
Author(s):  
Eric C. Freundt ◽  
Li Yu ◽  
Cynthia S. Goldsmith ◽  
Sarah Welsh ◽  
Aaron Cheng ◽  
...  
Keyword(s):  
Cell Death ◽  
Severe Acute Respiratory Syndrome ◽  
Vero Cells ◽  
Small Gtpase ◽  
Open Reading Frames ◽  
Accessory Proteins ◽  
Reading Frame ◽  
Golgi Fragmentation

ABSTRACT The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains eight open reading frames (ORFs) that encode novel proteins. These accessory proteins are dispensable for in vitro and in vivo replication and thus may be important for other aspects of virus-host interactions. We investigated the functions of the largest of the accessory proteins, the ORF 3a protein, using a 3a-deficient strain of SARS-CoV. Cell death of Vero cells after infection with SARS-CoV was reduced upon deletion of ORF 3a. Electron microscopy of infected cells revealed a role for ORF 3a in SARS-CoV induced vesicle formation, a prominent feature of cells from SARS patients. In addition, we report that ORF 3a is both necessary and sufficient for SARS-CoV-induced Golgi fragmentation and that the 3a protein accumulates and localizes to vesicles containing markers for late endosomes. Finally, overexpression of ADP-ribosylation factor 1 (Arf1), a small GTPase essential for the maintenance of the Golgi apparatus, restored Golgi morphology during infection. These results establish an important role for ORF 3a in SARS-CoV-induced cell death, Golgi fragmentation, and the accumulation of intracellular vesicles.

scholarly journals Comparative study of a 3CLpro inhibitor and remdesivir against both major SARS-CoV-2 clades in human airway models

2020 ◽  
Author(s):  
Maren de Vries ◽  
Adil S Mohamed ◽  
Rachel A Prescott ◽  
Ana M Valero-Jimenez ◽  
Ludovic Desvignes ◽  
...  
Keyword(s):  
Life Cycle ◽  
Comparative Analysis ◽  
Severe Acute Respiratory Syndrome ◽  
Comparative Study ◽  
In Vitro Models ◽  
Etiological Agent ◽  
Airway Epithelial ◽  
Lead Compound ◽  
Epithelial Cultures

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent of Coronavirus Disease 2019 (COVID-19), a pandemic that has claimed over 700,000 human lives. The only SARS-CoV-2 antiviral, for emergency use, is remdesivir, targeting the viral polymerase complex. PF-00835231 is a pre-clinical lead compound with an alternate target, the main SARS-CoV-2 protease 3CLpro (Mpro). Here, we perform a comparative analysis of PF-00835231 and remdesivir in A549+ACE2 cells, using isolates of two major SARS-CoV-2 clades. PF-00835231 is antiviral for both clades, and, in this assay, statistically more potent than remdesivir. A time-of-drug-addition approach delineates the timing of early SARS-CoV-2 life cycle steps and validates PF-00835231’s time of action. Both PF-00835231 and remdesivir potently inhibit SARS-CoV-2 in human polarized airway epithelial cultures. Thus, our study provides in vitro evidence for the potential of PF-00835231 as an effective antiviral for SARS-CoV-2, addresses concerns from non-human in vitro models, and supports further studies with this compound.

scholarly journals Screening of FDA-approved drugs using a MERS-CoV clinical isolate from South Korea identifies potential therapeutic options for COVID-19

2020 ◽  
Author(s):  
Meehyun Ko ◽  
So Young Chang ◽  
Soo Young Byun ◽  
Aleksandr Ianevski ◽  
Inhee Choi ◽  
...  
Keyword(s):  
Life Cycle ◽  
Clinical Isolate ◽  
Viral Life Cycle ◽  
Therapeutic Options ◽  
Added Value ◽  
South Korean ◽  
United States Food ◽  
Approved Drugs ◽  
Fda Approved Drugs

AbstractTherapeutic options for coronavirus remain limited. To address this unmet medical need, we screened 5,406 compounds, including United States Food and Drug Administration (FDA)- approved drugs and bioactives, for activity against a South Korean Middle East respiratory syndrome coronavirus (MERS-CoV) clinical isolate. Among 221 identified hits, 54 had therapeutic indexes (TI) greater than 6. Time-of-addition studies with selected drugs demonstrated eight and four FDA-approved drugs acted on the early and late stages of the viral life cycle, respectively. Confirmed hits included several cardiotonic agents (TI>100), atovaquone, an anti-malarial (TI>34), and ciclosonide, an inhalable corticosteroid (TI>6). Furthermore, utilizing the severe acute respiratory syndrome CoV-2 (SARS-CoV-2), combinations of remedesivir with selected dugs were evaluated, which identified ciclosonide and nelfinavir to be additive and synergistic drugs in vitro, respectively. Together, we screened FDA-approved drugs using patient-derived MERS-CoV, triaged hits to discriminate between early and late viral life cycle inhibitors, confirmed selected drugs using SARS-CoV-2, and demonstrated the added value of selected medications in combination with remedesivir. Our results identify potential therapeutic options for MERS-CoV infections, and provide a basis to treat coronavirus disease 2019 (COVID-19) and other coronavirus-related illnesses.

scholarly journals A Single Tyrosine in the Severe Acute Respiratory Syndrome Coronavirus Membrane Protein Cytoplasmic Tail Is Important for Efficient Interaction with Spike Protein

2009 ◽  
Vol 84 (4) ◽  
pp. 1891-1901 ◽  
Author(s):  
Corrin E. McBride ◽  
Carolyn E. Machamer
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Infectious Virus ◽  
Virus Assembly ◽  
Direct Interaction ◽  
Cytoplasmic Tail ◽  
Wild Type ◽  
Golgi Region ◽  
Sequence Requirements ◽  
Assembly Site

ABSTRACT Severe acute respiratory syndrome coronavirus (SARS-CoV) encodes 3 major envelope proteins: spike (S), membrane (M), and envelope (E). Previous work identified a dibasic endoplasmic reticulum retrieval signal in the cytoplasmic tail of SARS-CoV S that promotes efficient interaction with SARS-CoV M. The dibasic signal was shown to be important for concentrating S near the virus assembly site rather than for direct interaction with M. Here, we investigated the sequence requirements of the SARS-CoV M protein that are necessary for interaction with SARS-CoV S. The SARS-CoV M tail was shown to be necessary for S localization in the Golgi region when the proteins were exogenously coexpressed in cells. This was specific, since SARS-CoV M did not retain an unrelated glycoprotein in the Golgi. Importantly, we found that an essential tyrosine residue in the SARS-CoV M cytoplasmic tail, Y195, was important for S-M interaction. When Y195 was mutated to alanine, MY195A no longer retained S intracellularly at the Golgi. Unlike wild-type M, MY195A did not reduce the amount of SARS-CoV S carbohydrate processing or surface levels when the two proteins were coexpressed. Mutating Y195 also disrupted SARS-CoV S-M interaction in vitro. These results suggest that Y195 is necessary for efficient SARS-CoV S-M interaction and, thus, has a significant involvement in assembly of infectious virus.

scholarly journals Differential Requirements for Conserved E2 Binding Sites in the Life Cycle of Oncogenic Human Papillomavirus Type 31

1998 ◽  
Vol 72 (2) ◽  
pp. 1071-1077 ◽  
Author(s):  
Frank Stubenrauch ◽  
Hock B. Lim ◽  
Laimonis A. Laimins
Keyword(s):  
Human Papillomavirus ◽  
Life Cycle ◽  
Viral Replication ◽  
Binding Sites ◽  
Regulatory Region ◽  
Viral Life Cycle ◽  
Expression Vectors ◽  
Late Gene Expression ◽  
Fourfold Increase ◽  
Proximal Site

ABSTRACT Human papillomavirus (HPV) E2 proteins regulate viral replication by binding to sites in the upstream regulatory region (URR) and by complex formation with the E1 origin recognition protein. In the genital HPV types, the distribution and location of four E2 binding sites (BS1 to BS4) which flank a single E1 binding site are highly conserved. We have examined the roles of these four E2 sites in the viral life cycle of HPV type 31 (HPV31) by using recently developed methods for the biosynthesis of papillomaviruses from transfected DNA templates (M. G. Frattini et al., Proc. Natl. Acad. Sci. USA 93:3062–3067, 1996). In transient assays, no single site was found to be necessary for replication, and mutation of the early promoter-proximal site (BS4) led to a fourfold increase in replication. Cotransfection of the HPV31 wild-type (HPV-wt) and mutant genomes with expression vectors revealed that E1 stimulated replication of HPV31-wt as well as the HPV31-BS1, -BS2, and -BS3 mutants. In contrast, increased expression of E2 decreased replication of these genomes. Replication of the HPV31-BS4 mutant genome was not further increased by cotransfection of E1 expression vectors but was stimulated by E2 coexpression. In stably transfected normal human keratinocytes, mutation of either BS1, BS3, or BS4 resulted in integration of viral genomes into host chromosomes. In contrast, mutation of BS2 had no effect on stable maintenance of episomes or copy number. Following growth of stably transfected lines in organotypic raft cultures, the differentiation-dependent induction of late gene expression and amplification of viral DNA of the BS2 mutant was found to be similar to that of HPV31-wt. We were unable to find a role for BS2 in our assays for viral functions. We conclude that at least three of the four E2 binding sites in the URRs of HPVs are essential for the productive viral life cycle. The specific arrangement of E2 binding sites within the URR appears to be more important for viral replication than merely the number of sites.

scholarly journals Restriction of SARS-CoV-2 Replication by Targeting Programmed −1 Ribosomal Frameshifting In Vitro

2020 ◽  
Author(s):  
Yu Sun ◽  
Laura Abriola ◽  
Yulia V. Surovtseva ◽  
Brett D. Lindenbach ◽  
Junjie U. Guo
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
High Throughput ◽  
Open Reading Frame ◽  
Ribosomal Frameshifting ◽  
Reading Frame ◽  
Rna Pseudoknot ◽  
Proof Of Principle

SUMMARYTranslation of open reading frame 1b (ORF1b) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires programmed −1 ribosomal frameshifting (−1 PRF) promoted by an RNA pseudoknot. The extent to which SARS-CoV-2 replication may be sensitive to changes in −1 PRF efficiency is currently unknown. Through an unbiased, reporter-based high-throughput compound screen, we identified merafloxacin, a fluoroquinolone antibacterial, as a −1 PRF inhibitor of SARS-CoV-2. Frameshift inhibition by merafloxacin is robust to mutations within the pseudoknot region and is similarly effective on −1 PRF of other beta coronaviruses. Importantly, frameshift inhibition by merafloxacin substantially impedes SARS-CoV-2 replication in Vero E6 cells, thereby providing the proof of principle of targeting −1 PRF as an effective antiviral strategy for SARS-CoV-2.

Sign in / Sign up

Export Citation Format

Share Document