A Single Tyrosine in the Severe Acute Respiratory Syndrome Coronavirus Membrane Protein Cytoplasmic Tail Is Important for Efficient Interaction with Spike Protein (original) (raw)
Related papers
Virology Journal, 2014
Background: The SARS coronavirus (SARS-CoV) 3a protein functions as an ion channel, induces apoptosis and is important for viral pathogenesis. It is expressed on the cell surface and contains a tyrosine-based sorting motif and a di-acidic motif, which may be crucial for its intracellular trafficking. However the role of these motifs is not fully understood in the case of 3a protein. Methods: The subcellular distribution of the 3a protein was studied by immunofluorescence staining of cells transfected with wild type and mutant constructs along with markers for different intracellular compartments. Semi-quantitative RT-PCR was performed to estimate the mRNA where as western blotting was carried out to detect protein levels of wild type and mutant 3a proteins. In vitro transcription-translation was performed to estimate cell free protein synthesis. Results: While the wild type 3a protein is efficiently transported to the plasma membrane, the protein with mutations in the tyrosine and valine residues within the YXXV motif (ΔYXXΦ) accumulated in the Golgi compartment. However the 3a protein with mutations within the EXD di-acidic motif (ΔEXD) showed an intracellular distribution similar to the wild type protein. Increased retention of the ΔYXXΦ protein in the Golgi compartment also increased its association with lipid droplets. The ΔYXXΦ protein also expressed at significantly lower levels compared to the wild type 3a protein, which was reversed with Brefeldin A and Aprotinin. Conclusions: The data suggest that the YXXΦ motif of the SARS-CoV 3a protein is necessary for Golgi to plasma membrane transport, in the absence of which the protein is targeted to lysosomal degradation compartment via lipid droplets.
Journal of Virology, 2007
. Accumulation of the viral envelope proteins at this compartment is a prerequisite for virus assembly. Previously, we reported the identification of a dibasic motif (KxHxx) in the cytoplasmic tail of the SARS CoV spike (S) protein that was similar to a canonical dilysine ER retrieval signal. Here we demonstrate that this motif is a novel and functional ER retrieval signal which reduced the rate of traffic of the full-length S protein through the Golgi complex. The KxHxx motif also partially retained two different reporter proteins in the ERGIC region and reduced their rates of trafficking, although the motif was less potent than the canonical dilysine signal. The dibasic motif bound the coatomer complex I (COPI) in an in vitro binding assay, suggesting that ER retrieval may contribute to the accumulation of SARS CoV S protein near the virus assembly site for interaction with other viral structural proteins. In support of this, we found that the dibasic motif on the SARS S protein was required for its localization to the ERGIC/Golgi region when coexpressed with SARS membrane (M) protein.
Evolution of SARS-CoV-2 spike glycoprotein
2020
The spike glycoprotein (S) of SARS-CoV-2 mediates attachment of the virus to cell surface receptors and fusion between virus and cell membranes1. The receptor for SARS-CoV-2, like that for SARS-CoV, is the human cell-surface membrane protein ACE22–4. Membrane fusion activity, as for other class-1 fusion glycoproteins, requires S to be proteolytically cleaved into S1 and S2 that remain associated following cleavage4–7. SARS-CoV-2 is thought to have emerged from bats, possibly via a secondary host8,9. To better understand the transmission of SARS-CoV-2 we have determined the structure of its furin-cleaved S by cryoEM, which shows that cleavage at this polybasic amino-acid site increases the structural plasticity of the receptor binding region and facilitates the adoption of an open conformation that is required for it to bind to the ACE2 receptor. To investigate relationships between S proteins of SARS-CoV-2 and of the most closely related bat virus, RaTG138, we have determined and co...
Journal of Virology, 2011
The 2003 global outbreak of progressive respiratory failure was caused by a newly emerged virus, severe acute respiratory syndrome coronavirus (SARS-CoV). In contrast to many well-studied enveloped viruses that assemble and bud at the plasma membrane, coronaviruses assemble by budding into the lumen of the endoplasmic reticulum-Golgi intermediate compartment and are released from the cell by exocytosis. For this to occur, the viral envelope proteins must be efficiently targeted to the Golgi region of the secretory pathway. Although the envelope protein (E) makes up only a small percentage of the viral envelope, it plays an important, as-yet-undefined role in virus production. To dissect the targeting of the SARS-CoV E protein to the Golgi region, we exogenously expressed the protein and various mutants from cDNA and determined their localization using immunofluorescence microscopy and biochemical assays. We show that the cytoplasmic tail of the SARS-CoV E protein is sufficient to redirect a plasma membrane protein to the Golgi region. Through site-directed mutagenesis, we demonstrate that a predicted beta-hairpin structural motif in the tail is sufficient for Golgi complex localization of a reporter protein. This motif is conserved in E proteins of beta and gamma coronaviruses (formerly referred to as group 2 and 3 coronaviruses), where it also functions as a Golgi complex-targeting signal. Dissecting the mechanism of targeting of the SARS-CoV E protein will lead to a better understanding of its role in the assembly and release of virions.
SARS COV-2: Exploring the Virus of the Century
https://www.ijrrjournal.com/IJRR\_Vol.8\_Issue.8\_Aug2021/IJRR-Abstract062.html, 2021
Coronaviruses comprise a large family of viruses that cause respiratory and intestinal infections in animals and humans. This recent outbreak of unusual respiratory disease plaguing the entire world has been named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on the basis of phylogenetic analysis of related coronaviruses. Its transmission occurs mainly through airborn, fomite and other modes. Structurally, it is similar to other coronaviruses and has four major structural proteins; the spike surface glycoprotein (S), small envelope protein (E), matrix protein (M) and nucleocapsid protein (N). The M protein is most abundant and is responsible for intracellular formation of virus particles. S protein induces antibody generation and is involved in intracellular virus entry. Drug combinations are being tried on the basis of structural and genomic knowledge of the virus. Various researchers have found that the SARS CoV2 has many strains among which L type is most pathogenic and D614 type is most infective. All this information has been collected in this review to understand the virus behind this calamity in depth and to make it handy for the researchers to search literature related to SARS COV2.
Journal of Virology, 2008
This suggests that the mechanism of SARS-CoV assembly differs from that of other studied coronaviruses, which only require M and E proteins for VLP formation. When coexpressed, the native envelope trimeric S glycoprotein is incorporated onto VLPs. Interestingly, when a fluorescent protein tag is added to the C-terminal end of N or S protein, but not M protein, the chimeric viral proteins can be assembled within VLPs and allow visualization of VLP production and trafficking in living cells by state-of-the-art imaging technologies. Fluorescent VLPs will be used further to investigate the role of cellular machineries during SARS-CoV egress.
Viruses, 2012
A respiratory disease caused by a novel coronavirus, termed the severe acute respiratory syndrome coronavirus (SARS-CoV), was first reported in China in late 2002. The subsequent efficient human-to-human transmission of this virus eventually affected more than 30 countries worldwide, resulting in a mortality rate of ~10% of infected individuals. The spread of the virus was ultimately controlled by isolation of infected individuals and there has been no infections reported since April 2004. However, the natural reservoir of the virus was never identified and it is not known if this virus will re-emerge and, therefore, research on this virus continues. The SARS-CoV genome is about 30 kb in length and is predicted to contain 14 functional open reading frames (ORFs). The genome encodes for proteins that are homologous to known coronavirus proteins, such as the replicase proteins (ORFs 1a and 1b) and the four major structural proteins: nucleocapsid (N), spike (S), membrane (M) and e...
Role of structural and functional proteins of SARS -COV-2
GSC Biological and Pharmaceutical Sciences, 2020
Severe acute respiratory corona virus-2 (SARS-CoV-2) is a ribonucleic acid (RNA) virus with enveloped no-segmented positive sense belonging to a beta (β)-corona virus family. It has 29,903 nucleotides sized genome with 10 open reading frames (ORF). ORF1 (ab) encodes two polypeptides pp1a and pp1b cleaved into 16 functional proteins, which are mainly intended to form replication transcription complex (RTC). The cleavage process of pp1a and pp1b polypeptides to 16 functional proteins of SARs-CoV-2 is mainly facilitated by main protease and papain-like protease. The replication transcription complex (RTC) formed by the action of 16-functional proteins of SARs-CoV-2 is mainly involved as viral RNA synthesis machinery in the transcriptional and replication process of viral RNAs. ORF (2-10) encodes for structural (for example: spike (S), membrane (M), nucleocapsid (N), and envelop (E)) and accessory proteins of SARs-CoV-2. The main functions of structural proteins are viral assembly, viral coating, viral entry into host cells and assembly of the RNA genome. Accessory proteins are proteins that are not involved in the viral synthesis machinery, as 16 functional proteins, and in the viral assembly, coating, entry into host cells and packaging of Viral RNAs, as structural proteins. Rather, these are proteins that may play central role by enhancing viral assembly process, virulence and pathogenesis of SARs-CoV-2. Our aim in the current review was to elaborate the specific role of these structural and functional proteins on viral genomic replication and transcription, viral assembly, host cell attachment and pathogenesis. Multiple literatures have been reviewed to achieve the objective of this review.