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HBV RNA Encapsidation Signal Epsilon
The HBV RNA encapsidation signal epsilonHBV_epsilon is an element essential for HBV virus replication. It is an RNA structure situated near the 5' end of the HBV pregenomic RNA. The structure consists of a lower stem, a bulge region, an upper stem and a tri-loop. The structure was determined and refined through enzymatic probing and NMR spectroscopy. The closure of the tri-loop was not predicted by RNA structure prediction programs but observed in the NMR structure. The regions shown to be critical for encapsidation of the RNA in the viral lifecycle are the bulge, upper stem and tri-loop which interact with the terminal protein domain of the HBV viral polymerase. See also *Heron HBV RNA encapsidation signal epsilon The Avian HBV RNA encapsidation signal epsilon (AHBV epsilon) is an RNA structure that is shown to facilitate encapsidation of the pregenomic RNA required for viral replication. There are two main classes of encapsidation signals in avian he ... * Duck HB ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Structure
Protein secondary structure is the three dimensional form of ''local segments'' of proteins. The two most common secondary structural elements are 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 folds into its three dimensional tertiary structure. Secondary structure is formally defined by the pattern of hydrogen bonds between the amino hydrogen and carboxyl oxygen atoms in the peptide backbone. Secondary structure may alternatively be defined based on the regular pattern of backbone 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 Linderstrøm-Lang at Stanford in 1952. Other types of biopolymers such as nucleic acids also possess characteristic secondary structures. Types The most common secondary st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sequence Conservation
In evolutionary biology, conserved sequences are identical or similar Sequence (biology), sequences in nucleic acids (DNA sequence, DNA and RNA) or peptide sequence, proteins across species (homology (biology)#Orthology, orthologous sequences), or within a genome (homology (biology)#Paralogy, paralogous sequences), or between donor and receptor taxa (Sequence homology#Xenology, xenologous sequences). Conservation indicates that a sequence has been maintained by natural selection. A highly conserved sequence is one that has remained relatively unchanged far back up the phylogenetic tree, and hence far back in geological time. Examples of highly conserved sequences include the Ribosomal RNA, RNA components of ribosomes present in all domain (biology), domains of life, the homeobox sequences widespread amongst Eukaryotes, and the tmRNA in Bacteria. The study of sequence conservation overlaps with the fields of genomics, proteomics, evolutionary biology, phylogenetics, bioinformatics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cis-regulatory Element
''Cis''-regulatory elements (CREs) or ''Cis''-regulatory modules (CRMs) are regions of non-coding DNA which regulate the transcription of neighboring genes. CREs are vital components of genetic regulatory networks, which in turn control morphogenesis, the development of anatomy, and other aspects of embryonic development, studied in evolutionary developmental biology. CREs are found in the vicinity of the genes that they regulate. CREs typically regulate gene transcription by binding to transcription factors. A single transcription factor may bind to many CREs, and hence control the expression of many genes (pleiotropy). The Latin prefix ''cis'' means "on this side", i.e. on the same molecule of DNA as the gene(s) to be transcribed. CRMs are stretches of DNA, usually 100–1000 DNA base pairs in length, where a number of transcription factors can bind and regulate expression of nearby genes and regulate their transcription rates. They are labeled as ''cis'' because they are ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898,Dimmock p. 4 more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or ''virions'', consisti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatitis B Virus
''Hepatitis B virus'' (HBV) is a partially double-stranded DNA virus, a species of the genus '' Orthohepadnavirus'' and a member of the '' Hepadnaviridae'' family of viruses. This virus causes the disease hepatitis B. Disease Despite there being a vaccine to prevent Hepatitis B, HBV remains a global health problem. Hepatitis B can be acute and later become chronic, leading to other diseases and health conditions. In addition to causing hepatitis, infection with HBV can lead to cirrhosis and hepatocellular carcinoma. It has also been suggested that it may increase the risk of pancreatic cancer. Roles in disease Viral infection by ''Hepatitis B virus'' (HBV) causes many hepatocyte changes due to the direct action of a protein encoded by the virus, HBx, and to indirect changes due to a large increase in intracellular reactive oxygen species (ROS) after infection. HBx appears to dysregulate a number of cellular pathways. HBx causes dysregulation in part by binding to genomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Structure
Nucleic acid structure refers to the structure of nucleic acids such as DNA and RNA. Chemically speaking, DNA and RNA are very similar. Nucleic acid structure is often divided into four different levels: primary, secondary, tertiary, and quaternary. Primary structure Primary structure consists of a linear sequence of nucleotides that are linked together by phosphodiester bond. It is this linear sequence of nucleotides that make up the primary structure of DNA or RNA. Nucleotides consist of 3 components: # Nitrogenous base ## Adenine ## Guanine ## Cytosine ## Thymine (present in DNA only) ## Uracil (present in RNA only) # 5-carbon sugar which is called deoxyribose (found in DNA) and ribose (found in RNA). # One or more phosphate groups. The nitrogen bases adenine and guanine are purine in structure and form a glycosidic bond between their 9 nitrogen and the 1' -OH group of the deoxyribose. Cytosine, thymine, and uracil are pyrimidines, hence the glycosidic bonds form betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NMR Spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique to observe local magnetic fields around atomic nuclei. The sample is placed in a magnetic field and the NMR signal is produced by excitation of the nuclei sample with radio waves into nuclear magnetic resonance, which is detected with sensitive radio receivers. The intramolecular magnetic field around an atom in a molecule changes the resonance frequency, thus giving access to details of the electronic structure of a molecule and its individual functional groups. As the fields are unique or highly characteristic to individual compounds, in modern organic chemistry practice, NMR spectroscopy is the definitive method to identify monomolecular organic compounds. The principle of NMR usually involves three sequential steps: # The alignment (polarization) of the magnetic nuclear spins in an applied, constant magnetic field B0. # The p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Structure Prediction
Nucleic acid structure prediction is a computational method to determine ''secondary'' and ''tertiary'' nucleic acid structure from its sequence. Secondary structure can be predicted from one or several nucleic acid sequences. Tertiary structure can be predicted from the sequence, or by comparative modeling (when the structure of a homologous sequence is known). The problem of predicting nucleic acid secondary structure is dependent mainly on base pairing and base stacking interactions; many molecules have several possible three-dimensional structures, so predicting these structures remains out of reach unless obvious sequence and functional similarity to a known class of nucleic acid molecules, such as transfer RNA (tRNA) or microRNA (miRNA), is observed. Many secondary structure prediction methods rely on variations of dynamic programming and therefore are unable to efficiently identify pseudoknots. While the methods are similar, there are slight differences in the approach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heron HBV RNA Encapsidation Signal Epsilon
The Avian HBV RNA encapsidation signal epsilon (AHBV epsilon) is an RNA structure that is shown to facilitate encapsidation of the pregenomic RNA required for viral replication. There are two main classes of encapsidation signals in avian hepatitis B viruses - ''Duck hepatitis B virus'' (DHBV) and ''Heron hepatitis B virus'' (HHBV) like. DHBV is used as a model to understand human '' Hepatitis B virus''. Although studies have shown that the HHBV epsilon has less pairing in the upper stem than DHBV, this pairing is not absolutely required for DHBV infection in ducks. DHBV epsilon consists of a stem structure, a bulge and an apical loop (Fig. 1). The RNA structure was determined by chemical probing, NMR analysis and by mutagenesis. HHBV epsilon also consists of a stem structure, a bulge and an apical loop (Fig. 2). The RNA structure has been determined by chemical probing and by mutagenesis. However, it has less base pairing in the upper stem than DHBV epsilon. Recent NMR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duck HBV RNA Encapsidation Signal Epsilon
The Avian HBV RNA encapsidation signal epsilon (AHBV epsilon) is an RNA structure that is shown to facilitate encapsidation of the pregenomic RNA required for viral replication. There are two main classes of encapsidation signals in avian hepatitis B viruses - ''Duck hepatitis B virus'' (DHBV) and ''Heron hepatitis B virus'' (HHBV) like. DHBV is used as a model to understand human '' Hepatitis B virus''. Although studies have shown that the HHBV epsilon has less pairing in the upper stem than DHBV, this pairing is not absolutely required for DHBV infection in ducks. DHBV epsilon consists of a stem structure, a bulge and an apical loop (Fig. 1). The RNA structure was determined by chemical probing, NMR analysis and by mutagenesis. HHBV epsilon also consists of a stem structure, a bulge and an apical loop (Fig. 2). The RNA structure has been determined by chemical probing and by mutagenesis. However, it has less base pairing in the upper stem than DHBV epsilon. Recent NMR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatitis B Virus PRE Alpha
The Hepatitis B virus PRE stem-loop alpha (HBV PRE SL alpha) is an RNA structure that is shown to play a role in nuclear export of HBV mRNAs. HBV PREalpha consists of a 30 nt stem-loop, with a 5 nt apical loop. The conserved stem-loop was predicted within the HBV PRE sequence and confirmed by mutagenesis. The exact role of this structure in nuclear export has not yet been determined. See also * Hepatitis B virus PRE beta *HBV RNA encapsidation signal epsilon The HBV RNA encapsidation signal epsilonHBV_epsilon is an element essential for Hepatitis B virus, HBV virus replication. It is an RNA structure situated near the 5' end of the Hepatitis B virus, HBV pregenomic RNA. The structure consists of a l ... * Hepatitis_B virus PRE 1151–1410 References Cis-regulatory RNA elements Hepatitis B virus {{molecular-cell-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hepatitis B Virus PRE Beta
The Hepatitis B virus PRE stem-loop beta (HBV PRE SL-beta) is an RNA structure that is shown to play a role in nuclear export of HBV mRNAs. The minimal HBV PREbeta structure consists of a 23 nt stem-loop, with a 9 nt apical loop. The conserved stem-loop was predicted within the HBV PRE sequence and confirmed by mutagenesis. See also * Hepatitis B virus PRE alpha *HBV RNA encapsidation signal epsilon The HBV RNA encapsidation signal epsilonHBV_epsilon is an element essential for Hepatitis B virus, HBV virus replication. It is an RNA structure situated near the 5' end of the Hepatitis B virus, HBV pregenomic RNA. The structure consists of a l ... * Hepatitis B virus PRE 1151–1410 References Cis-regulatory RNA elements Hepatitis B virus {{molecular-cell-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
