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.

Translational control by a small RNA: dendritic BC1 RNA targets the eukaryotic initiation factor 4A helicase mechanism.

Abstract: Translational repressors, increasing evidence suggests, participate in the regulation of protein synthesis at the synapse, thus providing a basis for the long-term plastic modulation of synaptic strength. Dendritic BC1 RNA is a non-protein-coding RNA that represses translation at the level of initiation. However, the molecular mechanism of BC1 repression has remained unknown. Here we identify the catalytic activity of eukaryotic initiation factor 4A (eIF4A), an ATP-dependent RNA helicase, as a target of BC1-mediated translational control. BC1 RNA specifically blocks the RNA duplex unwinding activity of eIF4A but, at the same time, stimulates its ATPase activity. BC200 RNA, the primate-specific BC1 counterpart, targets eIF4A activity in identical fashion, as a result decoupling ATP hydrolysis from RNA duplex unwinding. In vivo, BC1 RNA represses translation of a reporter mRNA with 5′ secondary structure. The eIF4A mechanism places BC RNAs in a central position to modulate protein synthesis in neurons.

Evolution of a T7 RNA polymerase variant that transcribes 2'-O-methyl RNA.

Abstract: Modified RNA and DNA molecules have novel properties that their natural counterparts do not possess, such as better resistance to degradation in cells and improved pharmacokinetic behavior. In particular, modifications at the 2'-OH of ribose are important for enhancing the stability of RNA. Unfortunately, it is difficult to enzymatically synthesize modified nucleic acids of any substantial length because natural polymerases incorporate modified nucleotides inefficiently. Previously, we reported an activity-based method for selecting functional T7 RNA polymerase variants based on the ability of a T7 RNA polymerase to reproduce itself. Here, we have modified the original procedure to identify polymerases that can efficiently incorporate multiple modified nucleotides at the 2' position of the ribose. Most important, our method allows the selection of polymerases that have good processivities and can be combined to simultaneously incorporate several different modified nucleotides in a transcript.

Genetic analysis of the compatibility between polymerase proteins from human and avian strains of influenza A viruses.

Abstract: In order to determine how efficiently the polymerase proteins derived from human and avian influenza A viruses can interact with each other in the context of a mammalian cell, a genetic system that allows the in vivo reconstitution of active ribonucleoproteins was used. The ability to achieve replication of a viral-like reporter RNA in COS-1 cells was examined with heterospecific mixtures of the core proteins (PB1, PB2, PA and NP) from two strains of human viruses (A/Puerto Rico/8/34 and A/Victoria/3/75), two strains of avian viruses (A/Mallard/NY/6750/78 and A/FPV/-Rostock/34), and a strain of avian origin (A/Hong Kong/156/97) that was isolated from the first human case of H5N1 influenza in Hong Kong in 1997. In accordance with published observations on reassortant viruses, PB2 amino acid 627 was identified as a major determinant of the replication efficiency of heterospecific complexes in COS-1 cells. Moreover, the results showed that replication of the viral-like reporter RNA was more efficient when PB2 and NP were both derived from the same avian or human virus or when PB1 was derived from an avian virus, whatever the origin of the other proteins. Furthermore, the PB1 and PB2 proteins from the A/Hong- Kong/156/97 virus exhibited intermediate properties with respect to the corresponding proteins from avian or human influenza viruses, suggesting that some molecular characteristics of PB1 and PB2 proteins might at least partially account for the ability of the A/Hong Kong/156/97 virus to replicate in humans.

Specific Interaction between RNA Phage Coat Proteins and RNA

Abstract: Publisher Summary This chapter describes the biochemistry of the interaction of phage coat protein with RNA and attempt to provide a molecular understanding of its high specificity. Coat protein binding is believed to serve two functions in the life cycle of the phage: 1) it acts as a translational repressor of the replicase gene early in infection, and 2) as an initiation site of phage assembly late in infection. This interaction has been extensively a prototype of sequence specific RNA-protein interactions. It is now clear that the phage coat proteins can be considered an example of a class of RNA hairpin binding proteins that are quite common in prokaryotes and eukaryotes. In case of bacteriophage coat protein, the coat protein assembles into phage-like capsids that can be purified by differential centrifugation and ion-exchange chromatography. Most coat proteins can be successfully renatured by the transfer from storage buffer directly into a variety of neutral buffers of moderate ionic strength. In many cases, these renatured proteins are fully active in both RNA binding and capsid assembly.

Increased sensitivity of cell-free protein synthesis to double-stranded RNA after interferon treatment

Abstract: NATURALLY occurring and synthetic double-stranded RNAs (dsRNAs) are interferon inducers1. They inhibit protein synthesis in animal cells2 and cell-free systems3–5. It is intriguing, therefore, that interferon treatment renders cells more sensitive to the toxic effects of dsRNA6, particularly as viral dsRNA may be involved in the replication of RNA viruses and has been isolated from DNA virus-infected cells7. Accordingly, the production of viral dsRNA in response to infection could bring about a general inhibition of protein synthesis in the interferon-treated cell, as is indeed observed in interferon-treated, vaccinia virus-infected mouse fibroblast L cells8,9. The cell dies but little virus is produced: an effective way of limiting a natural infection.