The short- and long-range RNA Interactome of SARS-CoV-2
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ABSTRACT: The Coronaviridae are a family of positive- strand RNA viruses that includes SARS-CoV-2, the etiologic agent of the COVID-19 pandemic. Bearing the largest single stranded RNA genome in nature, coronaviruses are critically dependent on long-distance RNA-RNA interactions to regulate the viral transcription and replication pathways. Here we experimentally mapped the in vivo long-range RNA interactome of the full-length SARS-CoV-2 genome and the subgenomic mRNAs. We uncover a network of RNA-RNA interactions spanning tens of thousands of nucleotides that facilitate the unique transcription mode of coronaviruses, and reveal that the viral genome adopts alternative topologies inside cells and undergoes genome cyclization. Moreover, we discover long RNA-bridges between adjacent open reading frames that encircle the programmed ribosomal frame-shifting element, and demonstrate their conservation in vivo for the related MERS-CoV. Finally, the SARS-CoV-2 genome and subgenomic mRNAs engage in different sets of interactions with cellular RNAs. Our findings illuminate RNA-based mechanisms governing replication, discontinuous transcription, and translation of coronaviruses, and will aid future efforts to develop antiviral strategies.
Project description:The COVID-19 pandemic has claimed the lives of more than one million people worldwide. The causative agent, SARS-CoV-2, is a member of the Coronaviridae family, which are viruses that cause respiratory infections of varying severity. The cellular host factors and pathways co-opted by SARS- CoV-2 and other coronaviruses in the execution of their life cycles remain ill-defined. To develop an extensive compendium of host factors required for infection by SARS-CoV-2 and three seasonal coronaviruses (HCoV-OC43, HCoV-NL63, and HCoV-229E), we performed parallel genome-scale CRISPR knockout screens. These screens uncovered multiple host factors and pathways with pan- coronavirus and virus-specific functional roles, including major dependency on glycosaminoglycan biosynthesis, SREBP signaling, BMP signaling, and glycosylphosphatidylinositol biosynthesis, as well as a requirement for several poorly characterized proteins. We identified an absolute requirement for the VTT-domain containing protein TMEM41B for infection by SARS-CoV-2 and three seasonal coronaviruses. This human Coronaviridae host factor compendium represents a rich resource to develop new therapeutic strategies for acute COVID-19 and potential future coronavirus spillover events.
Project description:The SARS-CoV-2 coronavirus, which causes the COVID-19 pandemic, is one of the largest positive strand RNA viruses. Here we developed a simplified SPLASH assay and comprehensively mapped the in vivo RNA-RNA interactome of SARS-CoV-2 RNA during the viral life cycle. We observed canonical and alternative structures including 3’-UTR and 5’-UTR, frameshifting element (FSE) pseudoknot and genome cyclization in cells and in virions. We provide the first evidence of comprehensive interactions between Transcription Regulating Sequences (TRS-L and TRS-Bs), which facilitate discontinuous transcription. In addition, we find alternative short and long distance arches around FSE, forming a “high-order pseudoknot” embedding FSE, which might help ribosome stalling at frameshift sites. We found that during packaging, SARS-CoV-2 genome RNA undergoes compaction while genome domains remain stable and genome cyclization is weakened. Our data provides a structural basis for the regulation of replication, discontinuous transcription and translational frameshifting describes dynamics on RNA structures during life cycle of SARS-CoV-2, and will help to develop antiviral strategies.
Project description:SARS-CoV-2 coronavirus is one of the largest RNA viruses (26-32kb) and has emerged as a major threat to global public health. The resulting pandemic has caused global societal and economic disruptions. Here, we investigate the intramolecular and intermolecular RNA interactions of wildtype and a 382 deletion SARS-CoV-2 virus inside cells. We identified twelve potentially functional structural elements along the SARS-CoV-2 genome and observed that subgenomic viral RNA (sgRNAs) contains different structures that could be important for their functions using direct RNA sequencing. Proximity ligation sequencing experiments identified hundreds of intramolecular and intermolecular pair-wise interactions within the virus genome and between virus and host cellular RNAs. SARS-CoV-2 binds strongly to mitochondrial and nucleolar RNAs including COX1 and SNORD27, and contains 130 2’O-methylation sites along its genome. 2’O-methylation sites along the virus RNA are enriched in the UTRs and associated with increased pair-wise interactions. SARS-CoV-2 infection also results in a global decrease of 2’O-methylation sites on host mRNAs, suggesting that binding of SARS-CoV-2 to snoRNAs could be a pro-viral mechanism to sequester methylation machinery away from host RNAs to methylate the virus genome. Collectively, these studies deepen our understanding of the molecular basis of SARS-CoV-2 pathogenicity, its cellular host factors and provides a platform for targeting the virus.
Project description:Convalescent sera of RT-PCR SARS-CoV-2 confirmed hospitalised patients were tested on the protein array to profile IgG, IgM, and IgA antibody levels against human coronaviruses.
Project description:The on-going COVID-19 pandemic requires a deeper understanding of the long-term antibody responses that persist following SARS-CoV-2 infection. To that end, we determined epitope-specific IgG antibody responses in COVID-19 convalescent sera collected at 5 months post-diagnosis and compared that to sera from naïve individuals. Each serum sample was reacted with a high-density peptide microarray representing the complete proteome of SARS-CoV-2 as 15 mer peptides with 11 amino acid overlap and homologs of spike glycoprotein, nucleoprotein, membrane protein, and envelope small membrane protein from related human coronaviruses. Binding signatures were compared between COVID-19 convalescent patients and naïve individuals using the web service tool EPIphany.
Project description:SARS-CoV-2, the causative agent of COVID-19, is a positive-sense, single-stranded RNA virus that causes a spectrum of disease severity, from asymptomatic infection to severe illness to long-term sequelae. Similar to other human coronaviruses, SARS-CoV-2 proteins modulate host genomic responses through epigenomic modifications, facilitating viral replication and immune evasion. While the nucleocapsid protein is well known for its role in RNA stability and immune modulation, its impact on host chromatin organization remains unclear. To investigate this, we generated stable human alveolar cell lines expressing nucleocapsid proteins from endemic and pandemic human coronaviruses. Our analysis revealed that nucleocapsid proteins from all tested coronaviruses induced changes in nucleosome positioning and occupancy at specific gene promoters involved in coagulation pathways, hormone signaling, and innate immune responses. Additionally, SARS-CoV-2-specific alterations were identified in genes dysregulated in severe infections, such as suggesting a direct role for epigenomic modifications in disease pathophysiology. We also observed extensive changes in nucleosome susceptibility to nuclease digestion in SARS-CoV and SARS-CoV-2 samples that were not observed in common cold cell lines. Promoters with altered sensitivity and resistance to nuclease were linked to innate immune, metabolic, olfactory, and signaling pathways known to be dysregulated in severe COVID-19 and post-acute sequelae (PASC). These findings demonstrate that nucleocapsid protein expression alters chromatin structure at specific loci, implicating viral proteins in host genome dysregulation. Furthermore, we identified both shared and unique chromatin targets of SARS-CoV-2 and common cold coronaviruses, highlighting pathways for further investigation and potential therapeutic intervention.
Project description:We investigated the kinetics, breadth, magnitude, and level of cross-reactivity of IgG antibodies against SARS-CoV-2 and heterologous seasonal (HCoV-NL63, -229E, -OC43 and -HKU1) and epidemic coronaviruses (SARS-CoV, hCoV-MERS) at the clonal level in patients with mild or severe COVID-19 as well as in disease control patients. We assessed IgG antibody reactivity to nucleocapsid and spike antigens using protein microarray. A cutoff was set at the average plus 3 times the SD of 20 nonreactive cultures with a minimum MFI of 1000.
Project description:we resolved the RNA secondary structure of SARS-CoV-2 infected in Huh7.5.1 cells, in vitro structure of SARS-CoV-2 RNA purified from infected cells and refolded in test tube and viral RNA fragments of 7 coronaviruses including SARS-CoV-2, SARS-CoV and MERS-CoV based on in vivo click selective 2'-hydroxyl acylation and profiling experiment (icSHAPE). We built RNA structural model of SARS-CoV-2, found some functional structural elements, analysed the RNA structure conservation among different coronavirus. Also, we predicted RBP binding sites and identified some potential drug for CoVID-19 therapy.
Project description:We demonstrate that the histone demethylase KDM6A promotes infection of diverse coronaviruses, including SARS-CoV-1, SARS-CoV-2, MERS-CoV and mouse hepatitis virus (MHV) in a demethylase activity-independent manner
Project description:Direct RNA sequencing using an Oxford Nanopore MinION characterised the transcriptome of SARS-CoV-2 grown in Vero E6 cells. This cell line is being widely used to propagate the novel coronavirus. The viral transcriptome was analysed using a recently developed ORF-centric pipeline. This revealed the pattern of viral transcripts, (i.e. subgenomic mRNAs), generally fitted the predicted replication and transcription model for coronaviruses. A 24 nt in-frame deletion was detected in subgenomic mRNAs encoding the spike (S) glycoprotein. This feature was identified in over half of the mapped transcripts and was predicted to remove a proposed furin cleavage site from the S glycoprotein. This motif directs cleavage of the S glycoprotein into functional subunits during virus entry or exit. Cleavage of the S glycoprotein can be a barrier to zoonotic coronavirus transmission and affect viral pathogenicity. Allied to this transcriptome analysis, tandem mass spectrometry was used to identify over 500 viral peptides and 44 phosphopeptides, covering almost all of the proteins predicted to be encoded by the SARS-CoV-2 genome, including peptides unique to the deleted variant of the S glycoprotein. Detection of an apparently viable deletion in the furin cleavage site of the S glycoprotein reinforces the point that this and other regions of SARS-CoV-2 proteins may readily mutate. This is of clear significance given the interest in the S glycoprotein as a potential vaccine target and the observation that the furin cleavage site likely contributes strongly to the pathogenesis and zoonosis of this virus. The viral genome sequence should be carefully monitored during the growth of viral stocks for research, animal challenge models and, potentially, in clinical samples. Such variations may result in different levels of virulence, morbidity and mortality.