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Exoribonucleases
An exoribonuclease is an exonuclease ribonuclease, which are enzymes that degrade RNA by removing terminal nucleotides from either the 5' end or the 3' end of the RNA molecule. Enzymes that remove nucleotides from the 5' end are called ''5'-3' exoribonucleases'', and enzymes that remove nucleotides from the 3' end are called ''3'-5' exoribonucleases''. Exoribonucleases can use either water to cleave the nucleotide-nucleotide bond (which is called hydrolytic activity) or inorganic phosphate (which is called phosphorolytic activity). Hydrolytic exoribonucleases are classified under EC number 3.1 and phosphorolytic exoribonucleases under EC number 2.7.7. As the phosphorolytic enzymes use inorganic phosphate to cleave bonds they release nucleotide diphosphates, whereas the hydrolytic enzymes (which use water) release nucleotide monosphosphates. Exoribonucleases exist in all kingdoms of life, the bacteria, archaea, and eukaryotes. Exoribonucleases are involved in the degradation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exonuclease
Exonucleases are enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain. A hydrolyzing reaction that breaks phosphodiester bonds at either the 3′ or the 5′ end occurs. Its close relative is the endonuclease, which cleaves phosphodiester bonds in the middle (endo) of a polynucleotide chain. Eukaryotes and prokaryotes have three types of exonucleases involved in the normal turnover of mRNA: 5′ to 3′ exonuclease (Xrn1), which is a dependent decapping protein; 3′ to 5′ exonuclease, an independent protein; and poly(A)-specific 3′ to 5′ exonuclease. In both archaea and eukaryotes, one of the main routes of RNA degradation is performed by the multi-protein exosome complex, which consists largely of 3′ to 5′ exoribonucleases. Significance to polymerase RNA polymerase II is known to be in effect during transcriptional termination; it works with a 5' exonuclease (human gene Xrn2) to degrade the newly formed transcript ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoribonuclease I
5′-3′ exoribonuclease 1 (Xrn1) is a protein that in humans is encoded by the XRN1 gene. Xrn1 hydrolyses RNA in the 5′ to 3′ direction. Function This gene encodes a member of the 5′-3′ exonuclease family. The encoded protein may be involved in replication-dependent histone mRNA degradation, and interacts directly with the enhancer of mRNA-decapping protein 4. In addition to mRNA metabolism, a similar protein in yeast has been implicated in a variety of nuclear and cytoplasmic functions, including transcription, translation, homologous recombination, meiosis, telomere maintenance, and microtubule assembly. Mutations in this gene are associated with osteosarcoma, suggesting that the encoded protein may also play a role in bone formation. Alternative splicing results in multiple transcript variants. See also * Xrn2 5'-3' Exoribonuclease 2 (XRN2) also known as Dhm1-like protein is an exoribonuclease enzyme that in humans is encoded by the ''XRN2'' gene. The human g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNase R
RNase R, or Ribonuclease R, is a 3'-->5' exoribonuclease, which belongs to the RNase II superfamily, a group of enzymes that hydrolyze RNA in the 3' - 5' direction. RNase R has been shown to be involved in selective mRNA degradation, particularly of non stop mRNAs in bacteria. RNase R has homologues in many other organisms. When a part of another larger protein has a domain that is very similar to RNase R, this is called an RNase R domain. Role in ''trans''-translation and ribosomal quality control RNase R ensures translation accuracy, correct rRNA maturation and elimination of abnormal rRNAs, and is employed by the ''trans''-translation system to break down damaged mRNAs. In ''Escherichia coli,'' RNase R is a 92 kD protein, with the characteristic capacity to degrade structured RNA substrates without displaying sequence specificity. Therefore, RNase R acts over a range of substrates, such as, ribosomal, transfer, messenger and small non-coding RNAs. RNase R is associated with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNase T
Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2.7 (for the phosphorolytic enzymes) and 3.1 (for the hydrolytic enzymes) classes of enzymes. Function All organisms studied contain many RNases of two different classes, showing that RNA degradation is a very ancient and important process. As well as clearing of cellular RNA that is no longer required, RNases play key roles in the maturation of all RNA molecules, both messenger RNAs that carry genetic material for making proteins and non-coding RNAs that function in varied cellular processes. In addition, active RNA degradation systems are the first defense against RNA viruses and provide the underlying machinery for more advanced cellular immune strategies such as RNAi. Some cells also secrete copious quantities of non-specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNase D
Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2.7 (for the phosphorolytic enzymes) and 3.1 (for the hydrolytic enzymes) classes of enzymes. Function All organisms studied contain many RNases of two different classes, showing that RNA degradation is a very ancient and important process. As well as clearing of cellular RNA that is no longer required, RNases play key roles in the maturation of all RNA molecules, both messenger RNAs that carry genetic material for making proteins and non-coding RNAs that function in varied cellular processes. In addition, active RNA degradation systems are the first defense against RNA viruses and provide the underlying machinery for more advanced cellular immune strategies such as RNAi. Some cells also secrete copious quantities of non-specific RN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNase BN
Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2.7 (for the phosphorolytic enzymes) and 3.1 (for the hydrolytic enzymes) classes of enzymes. Function All organisms studied contain many RNases of two different classes, showing that RNA degradation is a very ancient and important process. As well as clearing of cellular RNA that is no longer required, RNases play key roles in the maturation of all RNA molecules, both messenger RNAs that carry genetic material for making proteins and non-coding RNAs that function in varied cellular processes. In addition, active RNA degradation systems are the first defense against RNA viruses and provide the underlying machinery for more advanced cellular immune strategies such as RNAi. Some cells also secrete copious quantities of non-specific RN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoribonuclease II
Exoribonuclease II (, ''ribonuclease II'', ''ribonuclease Q'', ''BN ribonuclease'', ''Escherichia coli exo-RNase II'', ''RNase II'', ''exoribonuclease (misleading)'', ''5'-exoribonuclease'') is an enzyme. This enzyme catalyses the following chemical reaction : Exonucleolytic cleavage in the 3'- to 5'-direction to yield nucleoside 5'-phosphates This enzyme has preference for single-stranded RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra .... See also * 5'-3' exoribonuclease 2 References External links * {{Portal bar, Biology, border=no EC 3.1.13 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribonuclease
Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2.7 (for the phosphorolytic enzymes) and 3.1 (for the hydrolytic enzymes) classes of enzymes. Function All organisms studied contain many RNases of two different classes, showing that RNA degradation is a very ancient and important process. As well as clearing of cellular RNA that is no longer required, RNases play key roles in the maturation of all RNA molecules, both messenger RNAs that carry genetic material for making proteins and non-coding RNAs that function in varied cellular processes. In addition, active RNA degradation systems are the first defense against RNA viruses and provide the underlying machinery for more advanced cellular immune strategies such as RNAi. Some cells also secrete copious quantities of non-specific RN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polynucleotide Phosphorylase
Polynucleotide Phosphorylase (PNPase) is a bifunctional enzyme with a phosphorolytic 3' to 5' exoribonuclease activity and a 3'-terminal oligonucleotide polymerase activity. That is, it dismantles the RNA chain starting at the 3' end and working toward the 5' end. It also synthesizes long, highly heteropolymeric tails ''in vivo''. It accounts for all of the observed residual polyadenylation in strains of ''Escherichia coli'' missing the normal polyadenylation enzyme. Discovered by Marianne Grunberg-Manago working in Severo Ochoa's lab in 1955, the RNA-polymerization activity of PNPase was initially believed to be responsible for DNA-dependent synthesis of messenger RNA, a notion that got disproved by the late 1950s. It is involved in mRNA processing and degradation in bacteria, plants, and animals. In humans, the enzyme is encoded by the gene. In its active form, the protein forms a ring structure consisting of three PNPase molecules. Each PNPase molecule consists of two RNase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoribonuclease
An endoribonuclease is a ribonuclease endonuclease. It cleaves either single-stranded or double-stranded RNA, depending on the enzyme. Example includes both single proteins such as RNase III, RNase A, RNase T1, RNase T2 and RNase H and also complexes of proteins with RNA such as RNase P and the RNA-induced silencing complex. Further examples include endoribonuclease XendoU found in frogs (''Xenopus ''Xenopus'' () (Gk., ξενος, ''xenos''=strange, πους, ''pous''=foot, commonly known as the clawed frog) is a genus of highly aquatic frogs native to sub-Saharan Africa. Twenty species are currently described within it. The two best-known ...''). External links * {{Nucleases EC 3.1 Ribonucleases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligoribonuclease
Oligonucleotidase (, ''oligoribonuclease'') is an exoribonuclease derived from ''Flammulina velutipes''. This enzyme catalyses the following chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ... : 3'-end directed exonucleolytic cleavage of viral RNA-DNA hybrid References External links * * EC 3.1.13 {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclease
A nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously effect single and double stranded breaks in their target molecules. In living organisms, they are essential machinery for many aspects of DNA repair. Defects in certain nucleases can cause genetic instability or immunodeficiency. Nucleases are also extensively used in molecular cloning. There are two primary classifications based on the locus of activity. Exonucleases digest nucleic acids from the ends. Endonucleases act on regions in the ''middle'' of target molecules. They are further subcategorized as deoxyribonucleases and ribonucleases. The former acts on DNA, the latter on RNA. History In the late 1960s, scientists Stuart Linn and Werner Arber isolated examples of the two types of enzymes responsible for phage growth restriction in Escherichia coli ( E. coli) bacteria. One of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
