Ribonuclease, abbreviated commonly as RNase, is a
nucleasethat catalyzes the degradation of RNAinto 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.
All organisms studied contain many RNases of many different classes, showing that RNA degradation is a very ancient and important process. As well as cleaning 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 a first defence against RNA viruses, and provide the underlying machinary for more advanced cellular immune strategies such as RNAi.
Some cells also secrete copious quantities of non-specific RNases such as A and T1. RNases are therefore extremely common, resulting in very short lifespans for any RNA that is not in a protected environment. It is worth noting that all intracellular RNAs are protected from RNase activity by a number of strategies including 5' end capping, 3' end
polyadenylation, and folding within an RNA protein complex ( ribonucleoproteinparticle or RNP).
Another mechanism of protection is
ribonuclease inhibitor(RI), which comprises a relatively large fraction of cellular protein (~0.1%) in some cell types, and which binds to certain ribonucleases with the highest affinity of any protein-protein interaction; the dissociation constantfor the RI-RNase A complex is ~20 fM under physiological conditions. RI is used in most laboratories that study RNA to protect their samples against degradation from environmental RNases.
restriction enzymes, which cleave highly specific sequences of double-stranded DNA, a variety of endoribonucleases have been recently classified which recognize and cleave specific sequences of single-stranded RNA.
RNases play a critical role in many biological processes, including
angiogenesisand self-incompatibilityin flowering plants (angiosperms). Additionally, RNases in prokaryotic toxin-antitoxin systems are proposed to function as plasmidstability loci, and as stress-response elements when present on the chromosome.
Major types of endoribonucleases
*: RNase A is an RNase that is commonly used in research. RNase A (e.g., bovine pancreatic ribonuclease A: PDB|2AAS) is one of the hardiest enzymes in common laboratory usage; one method of isolating it is to boil a crude cellular extract until all enzymes other than RNase A are denatured. It is sequence specific for single stranded RNAs. It cleaves 3'end of unpaired C and U residues, leaving a 3'-phosphorylated product, via a 2',3'-cyclic monophosphate.
RNase His a ribonuclease that cleaves the RNA in a DNA/RNA duplex to produce ssDNA. RNase H is a non-specific endonuclease and catalyzes the cleavage of RNA via a hydrolytic mechanism, aided by an enzyme-bound divalent metal ion. RNase H leaves a 5'-phosphorylated product.
EC number3.1.??: RNase Icleaves 3'-end of ssRNA at all dinucleotide bonds leaving a 5' hydroxyl, and 3' phosphate, via a 2',3'-cyclic monophosphate intermediate.
RNase IIIis a type of ribonuclease that cleaves rRNA (16s rRNA and 23s rRNA) from transcribed polycistronic RNA operon in prokaryotes. It also digests double strands RNA (dsRNS)-Dicer family of RNAse, cutting pre-miRNA (60-70bp long) at a specific site and transforming it in miRNA (22-30bp), that is actively involved in the regulation of transcription and mRNA life-time.
EC number3.1.??: RNase Lis an interferon-induced nuclease which, upon activation, destroys all RNA within the cell
RNase Pis a type of ribonuclease and is currently under heavy research. RNase P is unique from other RNases in that it is a ribozyme– a ribonucleic acid that acts as a catalyst in the same way that a proteinbased enzyme would. Its function is to cleave off an extra, or precursor, sequence of RNA on tRNAmolecules. Further RNase P is one of two known multiple turnover ribozymes in nature (the other being the ribosome).
EC number3.1.??: RNase PhyMis sequence specific for single stranded RNAs. It cleaves 3'-end of unpaired A and U residues.
RNase T1is sequence specific for single stranded RNAs. It cleaves 3'-end of unpaired G residues.
RNase T2is sequence specific for single stranded RNAs. It cleaves 3'-end of all 4 residues, but preferentially 3'-end of As.
RNase U2is sequence specific for single stranded RNAs. It cleaves 3'-end of unpaired A residues.
RNase V1is non-sequence specific for double stranded RNAs. It cleaves base-paired nucleotide residues.
Major types of exoribonucleases
EC numberEC number|18.104.22.168: Polynucleotide Phosphorylase (PNPase)functions both as an exonucleaseas well as a nucleotidyltransferase.
EC numberEC number|22.214.171.124: RNase PHfunctions both as an exonucleaseas well as a nucleotidyltransferase.
EC number3.1.??: RNase IIis responsible for the processive 3'-to-5' degradation of single-stranded RNA.
EC number3.1.??: RNase Ris a close homolog of RNase II, but it can, unlike RNase II, degrade RNA with secondary structures without help of accessory factors.
EC numberEC number|126.96.36.199: RNase Dis involved in the 3'-to-5' processing of pre-tRNAs.
EC number3.1.??: RNase Tis the major contributor for the 3'-to-5' maturation of many stable RNAs.
Oligoribonucleasedegrades short oligonucleotides to mononucleotides.
Exoribonuclease Idegrades single-stranded RNA from 5'-to-3', exists only in eukaryotes.
Exoribonuclease IIis a close homolog of Exoribonuclease I.
* [http://www.chem.qmul.ac.uk/iubmb/enzyme/EC3/1/ IUBMB Enzyme Database for EC 3.1]
* [http://www.ebi.ac.uk/intenz/query?cmd=SearchEC&ec=3.1 Integrated Enzyme Database for EC 3.1]
* D'Alessio G and Riordan JF, eds. (1997) "Ribonucleases: Structures and Functions", Academic Press.
* Gerdes K, Christensen SK and Lobner-Olesen A (2005). "Prokaryotic toxin-antitoxin stress response loci". Nat. Rev. Microbiol. (3): 371-382.
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ribonucléase — [ ribonykleaz ] n. f. • 1963; de ribo et nucléase ♦ Biochim. Enzyme qui catalyse l hydrolyse de l acide ribonucléique (cf. Désoxyribonucléase). ● ribonucléase nom féminin Enzyme (dont la séquence des acides aminés est entièrement connue) qui… … Encyclopédie Universelle
ribonuclease — ribonuclease. См. РНК аза. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
ribonuclease A — ribonuclease A. См. рибонуклеаза А. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
ribonuclease D — ribonuclease D. См. рибонуклеаза D. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
ribonuclease P — ribonuclease P. См. рибонуклеаза P. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
ribonuclease TI — ribonuclease TI. См. рибонуклеаза TI. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
Ribonucléase T1 — ● Ribonucléase T1 synonyme de takadiastase … Encyclopédie Universelle