Is there an RNA helicase?

Is there an RNA helicase?

RNA helicases constitute a large family of proteins with functions in all aspects of RNA metabolism. RNA helicases can have a variety of biochemical effects, such as unwinding or annealing RNA molecules, clamping protein complexes on RNA or remodelling ribonucleoprotein complexes.

What do rig like receptors do?

The RIG-I-like receptor (RLR) family of pattern recognition receptors (PRRs) is a group of cytosolic RNA helicase proteins that can identify viral RNA as nonself via binding to pathogen associated molecular pattern (PAMP) motifs within RNA ligands that accumulate during virus infection.

How is rig activated?

It is now known that RIG-I is activated by diverse positive- and negative-strand RNA viruses including influenza, Rift Valley fever, measles, Ebola, vesicular stomatitis (VSV), and hepatitis C viruses (Loo and Gale 2011). It is a large, multidomain protein (925 residues for human RIG-I, hRIG-I) (Fig.

Is it Rig 1 or RIG-I?

RIG-I (retinoic acid-inducible gene I) is a cytosolic pattern recognition receptor (PRR) responsible for the type-1 interferon (IFN1) response. RIG-I is an essential molecule in the innate immune system for recognizing cells that have been infected with a virus.

What do RNA helicase do?

RNA helicases are involved in shaping the form of RNA molecules, during all processes involving RNA, such as transcription, splicing, and translation.

Does RNA helicase unwind DNA?

RNA helicase A, also known as nuclear DNA helicase II or DHX9, is a superfamily 2 (SF2) helicase that unwinds DNA-DNA, RNA-RNA, and DNA-RNA strands with a 3′-5′ polarity [43].

What cells have rig-I-like receptors?

RIG-I and MDA5 are expressed in all cell types (60), but are most well-known for their functions inside innate immune cells, such as macrophages, neutrophils, and dendritic cells, as well as in other cells like mucosal epithelial cells. They are classified as ATP-dependent DExD/H box RNA helicases.

What are RNA sensors?

In both prokaryotic and eukaryotic genes, these elements act as sensors of external signals through mechanisms of molecular recognition that go beyond simple base pairing. These RNA sensors function within the cell to sense nutrients, temperature and stress.

What is RIG-I and MDA5?

RIG-I and MDA5 are the principal sensors of viral dsRNA in the cytoplasm. The interferon-dependent inflammatory response triggered by RLR ligand binding is one of the first and most important lines of defense against infection. RIG-I and MDA5 recognize distinct and complementary sets of viral dsRNA ligands.

What cells have rig-I like receptors?

Is helicase an RNA or DNA?

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.

How do RNA helicases work?

The RNA helicases promote forward steps, slow reverse steps or, through remodeling of RNA, open new reactions paths that facilitate correct folding 64, 77 (Box 3). Studies of pre-mRNA splicing also revealed that at least three RNA helicases function in proofreading events at various stages of the splicing reaction 78.

Where are rig like receptors found?

RIG-I antiviral signaling In the activated state the exposed RIG-I CARD domains interact with the CARD domains of MAVS (mitochondrial antiviral signaling protein, also known as IPS-1, VISA or Cardif) which sits on the outer surface of the mitochondria.

How are RNA viruses sensed by host cells?

Upon infection, both DNA and RNA viruses can be sensed by pattern recognition receptors (PRRs) in the cytoplasm or the nucleus to activate antiviral innate immunity.

Does immune system recognize RNA?

Immune sensing receptors can detect structural features such as dsRNA or 5′-triphosphate RNA, which indicate non-self, and indirectly or directly induce transcription factors that upregulate the expression of antiviral effector proteins, chemokines and cytokines, including type I interferon (IFN), to promote an …

What does Rig 1 detect?

RIG-I recognizes PAMP RNA ligands based on a level of specificity in terms of sequence composition, PAMP motif length, ss or dsRNA, and the presence of 5′ cap versus exposed 5′triphosphate (5′ppp). 5′ capped RNA does not trigger RIG-I signaling nor does RNA lacking exposed 5′ppp or 5′ diphosphosphate (5′pp) ( Fig.

Does transcription need helicase?

Known or putative helicases are required for general transcription initiation and for transcription-coupled DNA repair, and may play important roles in elongation, termination, and transcript stability.

What is helicase activity?

Helicases are motor proteins that unwind double stranded nucleic acids by utilizing free energy from ATP hydrolysis. They are ubiquitous enzymes in the cellular milieu functioning in diverse processes including DNA replication, DNA repair, RNA transcription and translation (1).