RNA-dependent RNA polymerase

About: RNA-dependent RNA polymerase is a research topic. Over the lifetime, 13904 publications have been published within this topic receiving 767954 citations. The topic is also known as: RdRp & RNA replicase.

RNAi-mediated viral immunity requires amplification of virus-derived siRNAs in Arabidopsis thaliana

Abstract: In diverse eukaryotic organisms, Dicer-processed, virus-derived small interfering RNAs direct antiviral immunity by RNA silencing or RNA interference Here we show that in addition to core dicing and slicing components of RNAi, the RNAi-mediated viral immunity in Arabidopsis thaliana requires host RNA-directed RNA polymerase (RDR) 1 or RDR6 to produce viral secondary siRNAs following viral RNA replication-triggered biogenesis of primary siRNAs We found that the two antiviral RDRs exhibited specificity in targeting the tripartite positive-strand RNA genome of cucumber mosaic virus (CMV) RDR1 preferentially amplified the 5'-terminal siRNAs of each of the three viral genomic RNAs, whereas an increased production of siRNAs targeting the 3' half of RNA3 detected in rdr1 mutant plants appeared to be RDR6-dependent However, siRNAs derived from a single-stranded 336-nucleotide satellite RNA of CMV were not amplified by either antiviral RDR, suggesting avoidance of the potent RDR-dependent silencing as a strategy for the molecular parasite of CMV to achieve preferential replication Our work thus identifies a distinct mechanism for the amplification of immunity effectors, which together with the requirement for the biogenesis of endogenous siRNAs, may play a role in the emergence and expansion of eukaryotic RDRs

Nucleoside derivatives as inhibitors of rna-dependent rna viral polymerase

Abstract: The present invention provides nucleoside compounds and certain derivatives thereof which are inhibitors of RNA-dependent RNA viral polymerase. These compounds are inhibitors of RNA-dependent RNA viral replication and are useful for the treatment of RNA-dependent RNA viral infection. They are particularly useful as inhibitors of hepatitis C virus (HCV) NS5B polymerase, as inhibitors of HCV replication, and/or for the treatment of hepatitis C infection. The invention also describes pharmaceutical compositions containing such nucleoside compounds alone or in combination with other agents active against RNA-dependent RNA viral infection, in particular HCV infection. Also disclosed are methods of inhibiting RNA-dependent RNA polymerase, inhibiting RNA-dependent RNA viral replication, and/or treating RNA-dependent RNA viral infection with the nucleoside compounds of the present invention.

Formation of plant RNA virus replication complexes on membranes: role of an endoplasmic reticulum-targeted viral protein.

Abstract: The mechanisms that direct positive-stranded RNA virus replication complexes to plant and animal cellular membranes are poorly understood. We describe a specific interaction between a replication protein of an RNA plant virus and membranes in vitro and in live cells. The tobacco etch virus (TEV) 6 kDa protein associated with membranes as an integral protein via a central 19 amino acid hydrophobic domain. In the presence or absence of other viral proteins, fluorescent fusion proteins containing the 6 kDa protein associated with large vesicular compartments derived from the endoplasmic reticulum (ER). Infection by TEV was associated with a collapse of the ER network into a series of discrete aggregated structures. Viral RNA replication complexes from infected cells were also associated with ER-like membranes. Targeting of TEV RNA replication complexes to membranous sites of replication is proposed to involve post-translational interactions between the 6 kDa protein and the ER.

Functional evidence for an RNA template in telomerase.

Abstract: The RNA moiety of the ribonucleoprotein enzyme telomerase from the ciliate Euplotes crassus was identified and its gene was sequenced. Functional analysis, in which oligonucleotides complementary to portions of the telomerase RNA were tested for their ability to prime telomerase in vitro, showed that the sequence 5' CAAAACCCCAAA 3' in this RNA is the template for synthesis of telomeric TTTTGGGG repeats by the Euplotes telomerase. The data provide a direct demonstration of a template function for a telomerase RNA and demarcate the outer boundaries of the telomeric template. Telomerase can now be defined as a specialized reverse transcriptase.

The Sulfolobus-“Caldariella” group: Taxonomy on the basis of the structure of DNA-dependent RNA polymerases

Abstract: The similarity of the morphology and of DNA composition, the homology of the component patterns of DNA-dependent RNA polymerases and their immunochemical crossreactivity support the conclusion that several extreme thermoacidophiles are related to each other. We name two new species of the genus Sulfolobus. The first, Sulfolobus solfataricus (DSM 1616 and DSM 1617) has the same GC content in its DNA and the same general properties as S. acidocaldarius, but differs significantly from the latter species in the molecular weights of the 11 components of its RNA polymerase and in the salt requirements of this enzyme. The second, Sulfolobus brierleyi, DSM 1651, differs from S. acidocaldarius in several respects. The cells show much less stability at neutral pH. The GC content is significantly lower. The RNA polymerase lacks two components present in the enzymes from the other species. The residual 9 components show larger size differences from the homologous subunits of the S. acidocaldarius enzyme. Like the enzyme from S. solfataricus, the polymerase from S. brierleyi yields an incomplete immunochemical crossreaction with an antibody against the RNA polymerase from S. acidocaldarius. The isolates DSM 1616 and DSM 1617 of Sulfolobus solfataricus are probably identical with or similar to the “Caldariella” strains MT 3 and MT 4, isolated by de Rosa et al. (1975). Like all other known archaebacterial RNA polymerases the enzymes from these species are insensitive to rifampicin and streptolydigin.