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Coronavirus Frameshifting Stimulation Element
In molecular biology, the coronavirus frameshifting stimulation element is a conserved stem-loop of RNA found in coronaviruses that can promote ribosomal frameshifting. Such RNA molecules interact with a downstream region to form a pseudoknot structure; the region varies according to the virus but pseudoknot formation is known to stimulate frameshifting. In the classical situation, a sequence 32 nucleotides downstream of the stem is complementary to part of the loop. In other coronaviruses, however, another stem-loop structure around 150 nucleotides downstream can interact with members of this family to form kissing stem-loops and stimulate frameshifting. Other RNA families identified in the coronavirus include the coronavirus 3′ stem-loop II-like motif (s2m), the coronavirus packaging signal and the coronavirus 3′ UTR pseudoknot. During protein synthesis, rapidly changing conditions in the cell can cause ribosomal pausing. In coronaviruses, this can affect growth rate an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Structure
Protein secondary structure is the three dimensional conformational isomerism, form of ''local segments'' of proteins. The two most common Protein structure#Secondary structure, secondary structural elements are alpha helix, alpha helices and beta sheets, though beta turns and omega loops occur as well. Secondary structure elements typically spontaneously form as an intermediate before the protein protein folding, folds into its three dimensional protein tertiary structure, tertiary structure. Secondary structure is formally defined by the pattern of hydrogen bonds between the Amine, amino hydrogen and carboxyl oxygen atoms in the peptide backbone chain, backbone. Secondary structure may alternatively be defined based on the regular pattern of backbone Dihedral angle#Dihedral angles of proteins, dihedral angles in a particular region of the Ramachandran plot regardless of whether it has the correct hydrogen bonds. The concept of secondary structure was first introduced by Kaj Ulrik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kissing Stem-loop
In genetics, a kissing stem-loop, or kissing stem loop interaction, is formed in ribonucleic acid (RNA) when two bases between two hairpin loops pair. These intra- and intermolecular kissing interactions are important in forming the tertiary or quaternary structure of many RNAs. RNA kissing interactions, also called loop-loop pseudoknots, occur when the unpaired nucleotides in one hairpin loop, base pair with the unpaired nucleotides in another hairpin loop. When the hairpin loops are located on separate RNA molecules, their intermolecular interaction is called a kissing complex. These interactions generally form between stem-loops. However, stable complexes have been observed containing only two intermolecular Watson–Crick base pairs. Biological significance RNA molecules perform their function in living cells by adopting specific and highly complex 3-dimensional structures. It is believed that recombination may be initiated by the kissing loops. Recombination is critical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus Packaging Signal
The Coronavirus packaging signal is a conserved cis-regulatory element found in Betacoronavirus (part of the Coronavirus subfamily of viruses). It has an important role in regulating the packaging of the viral genome into the capsid. As part of the viral life cycle, within the infected cell, the viral genome becomes associated with viral proteins and assembles into new infective progeny viruses. This process is called packaging and is vital for viral replication. The packaging signal is found in the positive-sense single-stranded RNA genome. It interacts with the viral proteins ( M and N) and ensures the selective packaging of viral RNA into virions. This RNA element is conserved in Embecovirus (previously known as lineage A Betacoronavirus), which includes mouse hepatitis virus (MHV), bovine coronavirus (BCoV), and human coronaviruses like HCoV-HKU1 and HCoV-OC43. Notably, this element is absent from the other viral lineages which have evolved separate packaging signals. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus 3′ Stem-loop II-like Motif (s2m)
The Coronavirus 3′ stem-loop II-like motif (also known as s2m) is a secondary structure motif identified in the 3′ UTR, 3′ untranslated region (3′UTR) of astrovirus, coronavirus and equine rhinovirus genomes. Its function is unknown, but various viral 3′ UTR regions have been found to play roles in viral replication and packaging. This motif appears to be conserved in both nucleotide sequence and secondary structure folding indicating a strong evolutionary selection for its Conserved sequence, conservation. The presence of this conserved motif in different viral families is suggested to be the result of at least two separate Genetic recombination, recombination events. To date s2m has been described in four families of positive sense single-stranded RNA viruses; ''Astrovirus, Astroviridae'', ''Caliciviridae'', ''Picornavirus, Picornaviridae'' and ''Coronavirus, Coronaviridae''. The viruses that contain s2m can infect a wide range of higher vertebrates, including birds, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus 3′ UTR Pseudoknot
The Coronavirus 3′ UTR pseudoknot is an RNA structure found in the coronavirus genome. Coronaviruses contain 30 kb single-stranded positive-sense RNA genomes. The 3′ UTR region of these coronavirus genomes contains a conserved ~55 nucleotide pseudoknot structure which is necessary for viral genome replication. The mechanism of cis-regulation is unclear, but this element is postulated to function in the plus-strand. Other RNA families identified in the coronavirus include the coronavirus frameshifting stimulation element, the coronavirus 3′ stem-loop II-like motif (s2m) The Coronavirus 3′ stem-loop II-like motif (also known as s2m) is a secondary structure motif identified in the 3′ UTR, 3′ untranslated region (3′UTR) of astrovirus, coronavirus and equine rhinovirus genomes. Its function is unknown, but ... and the coronavirus packaging signal. References External links * Cis-regulatory RNA elements Coronaviridae {{molecular-cell-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus 3′ UTR
Coronavirus genomes are positive-sense single-stranded RNA molecules with an untranslated region (UTR) at the 3′ end which is called the 3′ UTR. The 3′ UTR is responsible for important biological functions, such as viral replication. The 3′ UTR has a conserved RNA secondary structure but different Coronavirus genera ( Alpha-, Beta-, Gamma-, and Deltacoronaviruses) have different structural features described below. Alphacoronavirus 3′ UTR The 3′ UTR of Alphacoronaviruses consists of two small hairpins (PK-SL2) which can form an alternate conformation (PK-SL1) where the loop region of the second hairpin interacts with the stem of the first hairpin (see Coronavirus 3′ UTR pseudoknot). PK-SL2 has been confirmed in HCoV-229E and HCoV-NL63 by in vitro structure probing experiments. Downstream of this pseudoknot lies the hypervariable region (HVR), which is supported by many covarying base pairs in alphacoronaviruses. Further, a conserved octanucleotide sequence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus 5′ UTR
Coronavirus genomes are positive-sense single-stranded RNA molecules with an untranslated region (UTR) at the 5′ end which is called the 5′ UTR. The 5′ UTR is responsible for important biological functions, such as viral replication, transcription and packaging. The 5′ UTR has a conserved RNA secondary structure but different Coronavirus genera ( Alpha-, Beta-, Gamma-, and Deltacoronaviruses) have different structural features described below. Alphacoronavirus 5′ UTR The first 150 to 200 nucleotides within the 5′ UTR of Alphacoronaviruses are highly structured and shown to be conserved on the structural level. The 5′ UTRs are predicted to contain three conserved stem-loops: * SL1 is important for viral replication, most likely playing a role in the template-switch of viral subgenomic RNA (sgRNA) transcription. Mutations of the upper part of SL1 seem to have a higher impact of viral replication level. * SL2 is crucial for viral viability. Nucleotides are in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slippery Sequence
A slippery sequence is a small section of codon nucleotide sequences (usually UUUAAAC) that controls the rate and chance of ribosomal frameshifting. A slippery sequence causes a faster ribosomal transfer which in turn can cause the reading ribosome to "slip." This allows a tRNA to shift by 1 base (−1) after it has paired with its anticodon, changing the reading frame. A −1 frameshift triggered by such a sequence is a Programmed −1 Ribosomal Frameshift. It is followed by a spacer region, and an RNA secondary structure. Such sequences are common in virus polyproteins. The frameshift occurs due to wobble pairing. The Gibbs free energy of secondary structures downstream give a hint at how often frameshift happens. Tension on the mRNA molecule also plays a role. A list of slippery sequences found in animal viruses is available from Huang et al. Slippery sequences that cause a 2-base slip (−2 frameshift) have been constructed out of the HIV UUUUUUA sequence. See also *Nuclei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal Pause
Ribosomal pause refers to the queueing or stacking of ribosomes during translation of the nucleotide sequence of mRNA transcripts. These transcripts are decoded and converted into an amino acid sequence during protein synthesis by ribosomes. Due to the pause sites of some mRNA's, there is a disturbance caused in translation. Ribosomal pausing occurs in both eukaryotes and prokaryotes. A more severe pause is known as a ribosomal stall. It's been known since the 1980s that different mRNAs are translated at different rates. The main reason for these differences was thought to be the concentration of varieties of rare tRNAs limiting the rate at which some transcripts could be decoded. However, with research techniques such as ribosome profiling, it was found that at certain sites there were higher concentrations of ribosomes than average, and these pause sites were tested with specific codons. No link was found between the occupancy of specific codons and amount of their tRNAs. Thus, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus 3′ UTR Pseudoknot
The Coronavirus 3′ UTR pseudoknot is an RNA structure found in the coronavirus genome. Coronaviruses contain 30 kb single-stranded positive-sense RNA genomes. The 3′ UTR region of these coronavirus genomes contains a conserved ~55 nucleotide pseudoknot structure which is necessary for viral genome replication. The mechanism of cis-regulation is unclear, but this element is postulated to function in the plus-strand. Other RNA families identified in the coronavirus include the coronavirus frameshifting stimulation element, the coronavirus 3′ stem-loop II-like motif (s2m) The Coronavirus 3′ stem-loop II-like motif (also known as s2m) is a secondary structure motif identified in the 3′ UTR, 3′ untranslated region (3′UTR) of astrovirus, coronavirus and equine rhinovirus genomes. Its function is unknown, but ... and the coronavirus packaging signal. References External links * Cis-regulatory RNA elements Coronaviridae {{molecular-cell-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus Packaging Signal
The Coronavirus packaging signal is a conserved cis-regulatory element found in Betacoronavirus (part of the Coronavirus subfamily of viruses). It has an important role in regulating the packaging of the viral genome into the capsid. As part of the viral life cycle, within the infected cell, the viral genome becomes associated with viral proteins and assembles into new infective progeny viruses. This process is called packaging and is vital for viral replication. The packaging signal is found in the positive-sense single-stranded RNA genome. It interacts with the viral proteins ( M and N) and ensures the selective packaging of viral RNA into virions. This RNA element is conserved in Embecovirus (previously known as lineage A Betacoronavirus), which includes mouse hepatitis virus (MHV), bovine coronavirus (BCoV), and human coronaviruses like HCoV-HKU1 and HCoV-OC43. Notably, this element is absent from the other viral lineages which have evolved separate packaging signals. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronavirus 3′ Stem-loop II-like Motif (s2m)
The Coronavirus 3′ stem-loop II-like motif (also known as s2m) is a secondary structure motif identified in the 3′ UTR, 3′ untranslated region (3′UTR) of astrovirus, coronavirus and equine rhinovirus genomes. Its function is unknown, but various viral 3′ UTR regions have been found to play roles in viral replication and packaging. This motif appears to be conserved in both nucleotide sequence and secondary structure folding indicating a strong evolutionary selection for its Conserved sequence, conservation. The presence of this conserved motif in different viral families is suggested to be the result of at least two separate Genetic recombination, recombination events. To date s2m has been described in four families of positive sense single-stranded RNA viruses; ''Astrovirus, Astroviridae'', ''Caliciviridae'', ''Picornavirus, Picornaviridae'' and ''Coronavirus, Coronaviridae''. The viruses that contain s2m can infect a wide range of higher vertebrates, including birds, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
