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: The isolation of an RNA polymerase ribozyme called B6.61 that exhibits superior extension and fidelity relative to its progenitor, the Round-18 polymerase, demonstrates the feasibility of evolving an artificial RNA replicase Ribozyme in the foreseeable future.
Abstract: Our current understanding of biology suggests that early life relied predominantly on RNA for catalysis and replication. Here, we report the isolation of an RNA polymerase ribozyme called B6.61 that exhibits superior extension and fidelity relative to its progenitor, the Round-18 polymerase. The B6.61 polymerase was selected from a mutagenized pool containing ; 9 3 10 14 sequence variants through the use of a novel large-scale in vitro compartmentalization system. B6.61 polymerized all tested primer–template (PT) complexes faster than the Round-18 variant. For one PT, B6.61 exhibited dramatically faster elongation past one full helical turn and incorporated at least 20 nucleotides of sequence, setting a new extension record for an RNA polymerase ribozyme. The increased efficiency of the B6.61 construct was related to improvements in fidelity, with the new variant incorporating less incorrect wobble base pairs than its parent. This new polymerase demonstrates the feasibility of evolving an artificial RNA replicase ribozyme in the foreseeable future.
179 citations
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TL;DR: It is shown that recognition of promoters of this class depends on the “flexible flap” domain of the RNA polymerase β subunit, which is evolutionarily conserved and may facilitate promoter recognition by specificity factors in eukaryotes as well.
Abstract: In bacteria, promoter recognition depends on the RNA polymerase σ subunit, which combines with the catalytically proficient RNA polymerase core to form the holoenzyme. The major class of bacterial promoters is defined by two conserved elements (the –10 and –35 elements, which are 10 and 35 nucleotides upstream of the initiation point, respectively) that are contacted by σ in the holoenzyme. We show that recognition of promoters of this class depends on the “flexible flap” domain of the RNA polymerase β subunit. The flap interacts with conserved region 4 of σ and triggers a conformational change that moves region 4 into the correct position for interaction with the –35 element. Because the flexible flap is evolutionarily conserved, this domain may facilitate promoter recognition by specificity factors in eukaryotes as well.
179 citations
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TL;DR: It is shown that the antigenomic RNA of HDV is in fact the target for RNA editing, which is therefore a conversion of A to G, and the likelihood that double-stranded RNA adenosine deaminase specifically edits HDV antigenomicRNA is raised.
Abstract: RNA editing plays a central role in the life cycle of hepatitis D virus (HDV), a subviral human pathogen. Previous studies (J.L. Casey, K.F. Bergmann, T.L. Brown, and J.L. Gerin, Proc. Natl. Acad. Sci USA 89:7149-7153, 1992; H. Zheng, T.-B. Fu, D. Lazinski, and J. Taylor, J. Virol. 66:4693-4697, 1992) had concluded that the genomic RNA of HDV was the target for RNA editing and that the editing reaction was a conversion of U to C. However, we show here that the antigenomic RNA of HDV is in fact the target for HDV RNA editing, which is therefore a conversion of A to G. This result is verified by using an assay specific for editing on the antigenomic RNA and by analyzing the editing of site-directed mutant RNAs in transfected cells and in cell extracts. Because editing occurs in the absence of viral antigens and the specificity for the HDV editing target site is present even in extracts from Drosophila cells, it is likely that HDV RNA is edited by one or more cellular factors that are conserved among higher eukaryotes. These results raise the likelihood that double-stranded RNA adenosine deaminase specifically edits HDV antigenomic RNA.
179 citations
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University of Bern1, Federal Department of Home Affairs2, Kantonsspital St. Gallen3, Hannover Medical School4, University of Pennsylvania5, Utrecht University6, Singapore Immunology Network7, Cleveland Clinic8, Max Planck Society9, Washington University in St. Louis10, University of Giessen11, Cleveland Clinic Lerner Research Institute12, Friedrich Loeffler Institute13
TL;DR: It is shown that the coronavirus endonuclease (EndoU) activity is key to prevent early induction of double-stranded RNA (dsRNA) host cell responses, which suggests an evolutionary conserved viral function that has evolved to prevent RNA-based sensing of infection in vertebrate hosts.
Abstract: Coronaviruses are of veterinary and medical importance and include highly pathogenic zoonotic viruses, such as SARS-CoV and MERS-CoV. They are known to efficiently evade early innate immune responses, manifesting in almost negligible expression of type-I interferons (IFN-I). This evasion strategy suggests an evolutionary conserved viral function that has evolved to prevent RNA-based sensing of infection in vertebrate hosts. Here we show that the coronavirus endonuclease (EndoU) activity is key to prevent early induction of double-stranded RNA (dsRNA) host cell responses. Replication of EndoU-deficient coronaviruses is greatly attenuated in vivo and severely restricted in primary cells even during the early phase of the infection. In macrophages we found immediate induction of IFN-I expression and RNase L-mediated breakdown of ribosomal RNA. Accordingly, EndoU-deficient viruses can retain replication only in cells that are deficient in IFN-I expression or sensing, and in cells lacking both RNase L and PKR. Collectively our results demonstrate that the coronavirus EndoU efficiently prevents simultaneous activation of host cell dsRNA sensors, such as Mda5, OAS and PKR. The localization of the EndoU activity at the site of viral RNA synthesis-within the replicase complex-suggests that coronaviruses have evolved a viral RNA decay pathway to evade early innate and intrinsic antiviral host cell responses.
179 citations
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TL;DR: The data suggest that packaging of APO3G into HIV-1 NPC is enhanced by viral RNA, and a target sequence located within the 5′-untranslated region of the HIV- 1 RNA was identified to be necessary and sufficient for efficient APo3G packaging.
Abstract: APOBEC3G (APO3G) is a host cytidine deaminase that is incorporated into human immunodeficiency virus type 1 (HIV-1) particles. We report here that viral RNA promotes stable association of APO3G with HIV-1 nucleoprotein complexes (NPC). A target sequence located within the 5′-untranslated region of the HIV-1 RNA was identified to be necessary and sufficient for efficient APO3G packaging. Fine mapping revealed a sequence normally involved in viral genomic RNA dimerization and Gag binding to be important for APO3G packaging and association with viral NPC. Our data suggest that packaging of APO3G into HIV-1 NPC is enhanced by viral RNA.
179 citations