RNA-dependent RNA polymerase
RNA-dependent RNA polymerase (RDRP), or RNA replicase, is an
enzymethat catalyzes the replication of RNAfrom an RNA template. This is in contrast to a typical RNA polymerase, which catalyzes the transcription of RNA from a DNAtemplate.
Viral RDRPs were discovered in the early 1960s from studies on mengovirus and
polio viruswhen it was observed that these viruses were not sensitive to actinomycin D, a drug that inhibits cellular DNA directed RNA synthesis.This lack of sensitivity suggested that there was a virus specific enzyme that could copy RNA from an RNA template and not from a DNA template.
The most famous example of RDRP is the
polio virus. The virus is made up of RNA which enters the cell through receptor-mediated endocytosis. From there, the RNA is able to act as a template for complementary RNA synthesis, immediately. The complementary strand is then, itself, able to act as a template for the production of new viral genomes which are further packaged and released from the cell ready to infect more host cells. The advantage of this method of replication is that there is no DNA stage, replication is quick and easy. The disadvantage is that there is no 'back-up' DNA copy.
Many RDRPs are associated tightly with membranes and are therefore difficult to study. The best known RDRPs are polioviral 3Dpol, vesicular stomatitis virus L, and
hepatitis C virusNS5b protein. Eukaryotes also have RDRPs involved in RNA interference; these amplify microRNAs and small temporal RNAs and produce double-stranded RNA using small interfering RNAs as primers [cite journal |author=Iyer LM, Koonin EV, Aravind L |title=Evolutionary connection between the catalytic subunits of DNA-dependent RNA polymerases and eukaryotic RNA-dependent RNA polymerases and the origin of RNA polymerases |journal=BMC Struct. Biol. |volume=3 |issue= |pages=1 |year=2003 |month=January |pmid=12553882 |doi= |url=http://www.biomedcentral.com/1472-6807/3/1] [ [http://www.ebi.ac.uk/interpro/IEntry?ac=IPR007855 InterPro: RNA-dependent RNA polymerase, eukaryotic-type] , retrieved 6 April 2008]
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Look at other dictionaries:
RNA-dependent RNA polymerase — RNA dependent RNA polymerase. См. РНК репликаза. (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.
RNA-dependent DNA polymerase — See: reverse transcriptase … Glossary of Biotechnology
RNA polymerase II — (also called RNAP II and Pol II) is an enzyme found in eukaryotic cells. It catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA. [cite journal | author = Kronberg, R.D. | title = Eukaryotic… … Wikipedia
RNA polymerase — RNAP from T. aquaticus pictured during elongation. Portions of the enzyme were made transparent so as to make the path of RNA and DNA more clear. The magnesium ion (yellow) is located at the enzyme active site. RNA polymerase (RNAP or RNApol) is… … Wikipedia
RNA polymerase I — An impressive 50%+ of all RNA synthesis in a cell is accounted for by the transcription of rRNA. Eukaryotic cells have evolved a polymerase strictly dedicated to this pursuit.RNA polymerase I (also called Pol I) transcribes DNA to synthesize rRNA … Wikipedia
DNA-dependent RNA polymerase — DNA dependent RNA polymerase. См. ДНК зависимая РНК полимераза. (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.
RNA interference — (RNAi) is a mechanism that inhibits gene expression at the stage of translation or by hindering the transcription of specific genes. RNAi targets include RNA from viruses and transposons (significant for some forms of innate immune response), and … Wikipedia
RNA-induced transcriptional silencing — (RITS) is a form of RNA interference by which short RNA molecules such as small interfering RNA (siRNA) trigger the downregulation of transcription of a particular gene or genomic region. This is usually accomplished by posttranslational… … Wikipedia
Polymerase stuttering — is the process by which a polymerase transcribes a nucleotide several times without progressing further on the mRNA chain. It is often used in addition of poly A tails or capping mRNA chains by less complex organisms such as viruses. Process A… … Wikipedia
RNA replicase — RNA replicase. = RNA dependent RNA polymerase (см.). (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.