Sarbecovirus programmed ribosome frameshift RNA element folding studied by NMR spectroscopy and comparative analyses.

The programmed ribosomal frameshift (PRF) region is found in the RNA genome of all coronaviruses and shifts the ribosome reading frame through formation of a three-stem pseudoknot structure, allowing the translation of essential viral proteins. Using NMR spectroscopy, comparative sequence analyses and functional assays we show that, in the absence of the ribosome, a 123-nucleotide sequence encompassing the PRF element of SARS-CoV-2 adopts a well-defined two-stem loop structure that is conserved in all SARS-like coronaviruses. In this conformation, the attenuator hairpin and slippery site nucleotides are exposed in the first stem-loop and two pseudoknot stems are present in the second stem-loop, separated by an 8-nucleotide bulge.

SARS-CoV-2 Inhibitors Identified by Phenotypic Analysis of a Collection of Viral RNA-Binding Molecules.

Antiviral agents are needed for the treatment of SARS-CoV-2 infections and to control other coronavirus outbreaks that may occur in the future. Here we report the identification and characterization of RNA-binding compounds that inhibit SARS-CoV-2 replication. The compounds were detected by screening a small library of antiviral compounds previously shown to bind HIV-1 or HCV RNA elements with a live-virus cellular assay detecting inhibition of SARS-CoV-2 replication.

An unexpected RNA distal interaction mode found in an essential region of the hepatitis C virus genome.

The 3'X tail is a functionally essential 98-nt sequence located at the 3'-end of the hepatitis C virus (HCV) RNA genome. The domain contains two absolutely conserved dimer linkage sequence (DLS) and k nucleotide segments involved in viral RNA dimerization and in a distal base-pairing interaction with stem-loop 5BSL3.2, respectively.

Three-dimensional structure of the 3'X-tail of hepatitis C virus RNA in monomeric and dimeric states.

The 3'X domain is a 98-nt region located at the 3' end of hepatitis C virus genomic RNA that plays essential functions in the viral life cycle. It contains an absolutely conserved, 16-base palindromic sequence that promotes viral RNA dimerization, overlapped with a 7-nt tract implicated in a distal contact with a nearby functional sequence. Using small angle X-ray scattering measurements combined with model building guided by NMR spectroscopy, we have studied the stoichiometry, structure, and flexibility of domain 3'X and two smaller subdomain sequences as a function of ionic strength, and obtained a three-dimensional view of the full-length domain in its monomeric and dimeric states.

The conserved 3'X terminal domain of hepatitis C virus genomic RNA forms a two-stem structure that promotes viral RNA dimerization.

The 3'X domain of hepatitis C virus is a strongly conserved structure located at the 3' terminus of the viral genomic RNA. This domain modulates the replication and translation processes of the virus in conjunction with an upstream 5BSL3.2 stem-loop, and contains a palindromic sequence that facilitates RNA dimerization.