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.

Activation of MDA5 Requires Higher-Order RNA Structures Generated during Virus Infection

Abstract: Recognition of virus presence via RIG-I (retinoic acid inducible gene I) and/or MDA5 (melanoma differentiation-associated protein 5) initiates a signaling cascade that culminates in transcription of innate response genes such as those encoding the alpha/beta interferon (IFN-α/β) cytokines. It is generally assumed that MDA5 is activated by long molecules of double-stranded RNA (dsRNA) produced by annealing of complementary RNAs generated during viral infection. Here, we used an antibody to dsRNA to show that the presence of immunoreactivity in virus-infected cells does indeed correlate with the ability of RNA extracted from these cells to activate MDA5. Furthermore, RNA from cells infected with encephalomyocarditis virus or with vaccinia virus and precipitated with the anti-dsRNA antibody can bind to MDA5 and induce MDA5-dependent IFN-α/β production upon transfection into indicator cells. However, a prominent band of dsRNA apparent in cells infected with either virus does not stimulate IFN-α/β production. Instead, stimulatory activity resides in higher-order structured RNA that contains single-stranded RNA and dsRNA. These results suggest that MDA5 activation requires an RNA web rather than simply long molecules of dsRNA.

The la protein

Abstract: f Abstract Ubiquitous in eukaryotic cells, the La protein associates with the 3 termini of many newly synthesized small RNAs. RNAs bound by the La protein include all nascent transcripts made by RNA polymerase III as well as certain small RNAs synthesized by other RNA polymerases. Recent genetic and biochemical analyses have revealed that binding by the La protein protects the 3 ends of these RNAs from exonucleases. This La-mediated stabilization is required for the normal pathway of pre-tRNA maturation, facilitates assembly of small RNAs into functional RNA-protein complexes, and contributes to nuclear retention of certain small RNAs. Studies of mutant La proteins have given some insights into how the La protein specifically recognizes its RNA targets. However, many questions remain regarding the molecular mechanisms by which La protein binding influences multiple steps in small RNA biogenesis. This review focuses on the roles of the La protein in small RNA biogenesis and also discusses data that implicate the La protein in the translation of specific mRNAs.

Degradation of RNA in bacteria: comparison of mRNA and stable RNA

Abstract: Degradation of RNA plays a central role in RNA metabolism. In recent years, our knowledge of the mechanisms of RNA degradation has increased considerably with discovery of the participating RNases and analysis of mutants affected in the various degradative pathways. Among these processes, mRNA decay and stable RNA degradation generally have been considered distinct, and also separate from RNA maturation. In this review, each of these processes is described, as it is currently understood in bacteria. The picture that emerges is that decay of mRNA and degradation of stable RNA share many common features, and that their initial steps also overlap with those of RNA maturation. Thus, bacterial cells do not contain dedicated machinery for degradation of different classes of RNA or for different processes. Rather, only the specificity of the RNase and the accessibility of the substrate determine whether or not a particular RNA will be acted upon.