Coronaviruses (CoVs) are a family of positive-sense, single-stranded RNA viruses that cause disease in humans9, including SARS-CoV-2, the aetiological agent of the ongoing COVID-19 pandemic. The 5′ proximal two-thirds of the SARS-CoV-2 RNA genome contains two open reading frames that are translated by host ribosomes to form two large polyproteins. These polyproteins are cleaved by viral proteases to form 16 non-structural proteins (nsp1–16), some of which make up the replication–transcription complex (RTC). The CoV RNA genome, like eukaryotic mRNAs, contains a methylated guanosine linked to the first nucleotide of the RNA through a reverse 5′ to 5′ triphosphate linkage. Methylation of the ribose 2′-OH position of the first nucleotide completes the cap and protects the RNA from the host immune system. This 5′ cap is important for RNA stability, initiation of mRNA translation and protection from exonucleases. Thus, formation of the RNA cap is crucial for successful replication and transcription of the viral genome. A recent paper by Zan and coworkers published in Cell (10.1016/j.cell.2022.09.037) described a new mechanism for the capping of the viral genome by using cryoEM techniques. Here you can see one of the reported structures of the SARS-CoV-2 capping complex (PDB code: 8GWE)
#molecularart ... #immolecular ... #SARS-CoV-2 ... #genome ... #RNA .. #capping ... #complex ... #cryoem
Structure rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #SARS-CoV-2 ... #genome ... #RNA .. #capping ... #complex ... #cryoem
Structure rendered with @proteinimaging and depicted with @corelphotopaint
