RNA

About: RNA is a research topic. Over the lifetime, 111695 publications have been published within this topic receiving 5475262 citations. The topic is also known as: ribonucleic acid.

RNA-Catalyzed RNA Polymerization: Accurate and General RNA-Templated Primer Extension

Abstract: The RNA world hypothesis regarding the early evolution of life relies on the premise that some RNA sequences can catalyze RNA replication. In support of this conjecture, we describe here an RNA molecule that catalyzes the type of polymerization needed for RNA replication. The ribozyme uses nucleoside triphosphates and the coding information of an RNA template to extend an RNA primer by the successive addition of up to 14 nucleotides-more than a complete turn of an RNA helix. Its polymerization activity is general in terms of the sequence and the length of the primer and template RNAs, provided that the 3' terminus of the primer pairs with the template. Its polymerization is also quite accurate: when primers extended by 11 nucleotides were cloned and sequenced, 1088 of 1100 sequenced nucleotides matched the template.

The emerging field of RNA nanotechnology

Abstract: Like DNA, RNA can be designed and manipulated to produce a variety of different nanostructures. Moreover, RNA has a flexible structure and possesses catalytic functions that are similar to proteins. Although RNA nanotechnology resembles DNA nanotechnology in many ways, the base-pairing rules for constructing nanoparticles are different. The large variety of loops and motifs found in RNA allows it to fold into numerous complicated structures, and this diversity provides a platform for identifying viable building blocks for various applications. The thermal stability of RNA also allows the production of multivalent nanostructures with defined stoichiometry. Here we review techniques for constructing RNA nanoparticles from different building blocks, we describe the distinct attributes of RNA inside the body, and discuss potential applications of RNA nanostructures in medicine. We also offer some perspectives on the yield and cost of RNA production.

The RNA Helicase Lgp2 Inhibits TLR-Independent Sensing of Viral Replication by Retinoic Acid-Inducible Gene-I

Abstract: The paramyxovirus Sendai (SV), is a well-established inducer of IFN-alphabeta gene expression. In this study we show that SV induces IFN-alphabeta gene expression normally in cells from mice with targeted deletions of the Toll-IL-1 resistance domain containing adapters MyD88, Mal, Toll/IL-1R domain-containing adaptor inducing IFN-beta (TRIF), and TRIF-related adaptor molecule TLR3, or the E3 ubiquitin ligase, TNFR-associated factor 6. This TLR-independent induction of IFN-alphabeta after SV infection is replication dependent and mediated by the RNA helicase, retinoic acid-inducible gene-I (RIG-I) and not the related family member, melanoma differentiation-associated gene 5. Furthermore, we characterize a RIG-I-like RNA helicase, Lgp2. In contrast to RIG-I or melanoma differentiation-associated gene 5, Lgp2 lacks signaling caspase recruitment and activation domains. Overexpression of Lgp2 inhibits SV and Newcastle disease virus signaling to IFN-stimulated regulatory element- and NF-kappaB-dependent pathways. Importantly, Lgp2 does not prevent TLR3 signaling. Like RIG-I, Lgp2 binds double-stranded, but not single-stranded, RNA. Quantitative PCR analysis demonstrates that Lgp2 is present in unstimulated cells at a lower level than RIG-I, although both helicases are induced to similar levels after virus infection. We propose that Lgp2 acts as a negative feedback regulator of antiviral signaling by sequestering dsRNA from RIG-I.

Expression in brain of a messenger RNA encoding a novel neuropeptide homologous to calcitonin gene-related peptide.

Abstract: As a consequence of alternative RNA processing events, a single rat gene can generate messenger RNA's (mRNA's) encoding either calcitonin or a neuropeptide referred to as alpha-type calcitonin gene-related peptide (alpha-CGRP). An mRNA product of a related gene has been identified in rat brain and thyroid encoding the protein precursor of a peptide differing from alpha-CGRP by only a single amino acid. The RNA encoding this peptide, which is referred to as beta-CGRP, appears to be the only mature transcript of the beta-CGRP gene. Hybridization histochemistry reveals a similar distribution of alpha- and beta-CGRP mRNA's, but their relative levels of expression vary in different cranial nerve nuclei. Thus beta-CGRP is a new member of a family of related genes with potential functions in regulating the transduction of sensory and motor information.

Crystal structure of porcine ribonuclease inhibitor, a protein with leucine-rich repeats

Abstract: Ribonuclease inhibitor is a cytoplasmic protein that tightly binds and inhibits ribonucleases of the pancreatic ribonuclease superfamily. The primary sequence of this inhibitor contains leucine-rich repeats (LRRs); these motifs are present in many proteins that participate in protein-protein interactions and have different functions and cellular locations. In vivo, ribonuclease inhibitor may have a role in the regulation of RNA turnover in mammalian cells and in angiogenesis. To define the structural features of LRR proteins and to understand better the nature of the tight interaction of ribonuclease inhibitor with ribonucleases, we have determined the crystal structure of the porcine inhibitor. To our knowledge, this is the first three-dimensional structure of a protein containing LRRs and represents a new class of alpha/beta protein fold. Individual repeats constitute beta-alpha structural units that probably also occur in other proteins containing LRRs. The non-globular shape of the structure and the exposed face of the parallel beta-sheet may explain why LRRs are used to achieve strong protein-protein interactions. A possible ribonuclease-binding region incorporates the surface formed by the parallel beta-sheet and the beta alpha loops.