proteomics and biochemistry
Recorded terms: cell-free IRF3 dimerization assay; in vitro minus-strand synthesis assay; in vitro RNA polymerase assay; in vitro RNase cleavage assay; polymerase reconstitution assay; reconstituted influenza replication complex
Stress granules restrain rather than amplify double-stranded RNA sensing, and cells lacking the granule nucleators G3BP1 and G3BP2, UBAP2L or PKR respond to double-stranded RNA with excessive RIG-I-like receptor, PKR and OAS activation and MAVS-dependent apoptosis.
Restricting nucleoprotein availability in negative-sense RNA virus infections both blocks full-length genome replication and increases production of aberrant replication products that are sensed through RIG-I and MAVS, so a strong interferon response accompanies rather than follows successful infection.
RNase III nucleases, including human Drosha and homologues from bacteria, archaea, yeast and a urochordate, restrict positive-strand RNA viruses by recognizing unbranched RNA stem loops and impairing the viral polymerase, separably from microRNA biogenesis, catalysis and interferon.
Loss of the nuclear RNase III enzyme Drosha, but not of Dicer, increases RNA virus replication in mammalian fibroblasts, and diverse RNA viruses drive Drosha into the cytoplasm by CRM1-dependent export in a manner that does not require new protein synthesis, RIG-I, TBK1 or type I interferon signaling.
Influenza A virus small viral RNAs are shown to be synthesized from the complementary RNA intermediate, to load into the RNA binding cleft of the polymerase PA subunit, and to act there as segment-specific allosteric enhancers of full-length genome synthesis.