Topic
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.
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TL;DR: By mutation of the two largest subunits (NRPD1a and NRPD2), it is shown that Pol IV silences certain transposons and repetitive DNA in a short interfering RNA pathway involving RNA-dependent RNA polymerase 2 and Dicer-like 3.
Abstract: Plants encode subunits for a fourth RNA polymerase (Pol IV) in addition to the well-known DNA-dependent RNA polymerases I, II, and III. By mutation of the two largest subunits (NRPD1a and NRPD2), we show that Pol IV silences certain transposons and repetitive DNA in a short interfering RNA pathway involving RNA-dependent RNA polymerase 2 and Dicer-like 3. The existence of this distinct silencing polymerase may explain the paradoxical involvement of an RNA silencing pathway in maintenance of transcriptional silencing.
749 citations
TL;DR: A new protein has been isolated from E. coli which causes specific termination and release of RNA during synthesis in vitro and has been given the name ρ-factor.
Abstract: A new protein has been isolated from E. coli which causes specific termination and release of RNA during synthesis in vitro. It has been given the name ρ-factor.
739 citations
TL;DR: A chemical approach for 5' triphosphate oligoribonucleotide synthesis is established and it is found that synthetic single-stranded 5'Triphosphates were unable to bind and activate RIG-I, and the addition of the synthetic complementary strand resulted in optimal binding and activation of Rig-I.
723 citations
TL;DR: The cloning of qde-1, the first cellular component of the gene-silencing mechanism to be isolated, defines a new gene family conserved among different species including plants, animals and fungi, which is similar to an RNA-dependent RNA polymerase found in the tomato.
Abstract: In plants and fungi, the introduction of transgenes can lead to post-transcriptional gene silencing. This phenomenon, in which expression of the transgene and of endogenous genes containing sequences homologous to the transgene can be blocked, is involved in virus resistance and genome maintenance. Transgene-induced gene silencing has been termed quelling in Neurospora crassa and co-suppression in plants. Quelling-defective (qde) mutants of N. crassa, in which transgene-induced gene silencing is impaired, have been isolated. Here we report the cloning of qde-1, the first cellular component of the gene-silencing mechanism to be isolated, which defines a new gene family conserved among different species including plants, animals and fungi. The qde-1 gene product is similar to an RNA-dependent RNA polymerase found in the tomato. The identification of qde-1 strongly supports models that implicate an RNA-dependent RNA polymerase in the post-transcriptional gene-silencing mechanism. The presence of qde-1 homologues in a variety of species of plants and fungi indicates that a conserved gene-silencing mechanism may exist, which could have evolved to preserve genome integrity and to protect the genome against naturally occurring transposons and viruses.
717 citations
TL;DR: It is demonstrated that the combination of Zn2+ and PT at low concentrations reduces the replication of SARS-coronavirus (SARS-CoV) and equine arteritis virus (EAV) in cell culture and efficiently inhibits the RNA-synthesizing activity of the RTCs of both viruses.
Abstract: Increasing the intracellular Zn2+ concentration with zinc-ionophores like pyrithione (PT) can efficiently impair the replication of a variety of RNA viruses, including poliovirus and influenza virus. For some viruses this effect has been attributed to interference with viral polyprotein processing. In this study we demonstrate that the combination of Zn2+ and PT at low concentrations (2 µM Zn2+ and 2 µM PT) inhibits the replication of SARS-coronavirus (SARS-CoV) and equine arteritis virus (EAV) in cell culture. The RNA synthesis of these two distantly related nidoviruses is catalyzed by an RNA-dependent RNA polymerase (RdRp), which is the core enzyme of their multiprotein replication and transcription complex (RTC). Using an activity assay for RTCs isolated from cells infected with SARS-CoV or EAV—thus eliminating the need for PT to transport Zn2+ across the plasma membrane—we show that Zn2+ efficiently inhibits the RNA-synthesizing activity of the RTCs of both viruses. Enzymatic studies using recombinant RdRps (SARS-CoV nsp12 and EAV nsp9) purified from E. coli subsequently revealed that Zn2+ directly inhibited the in vitro activity of both nidovirus polymerases. More specifically, Zn2+ was found to block the initiation step of EAV RNA synthesis, whereas in the case of the SARS-CoV RdRp elongation was inhibited and template binding reduced. By chelating Zn2+ with MgEDTA, the inhibitory effect of the divalent cation could be reversed, which provides a novel experimental tool for in vitro studies of the molecular details of nidovirus replication and transcription.
715 citations