Reverse transcriptase / transcription

Reverse transcriptase (Section 28 13) Enzyme that catalyzes the transcription of RNA to DNA Ribozyme (Section 28 11) A polynucleotide that has catalytic activity... 

Reverse transcriptase (Section 28.13) Enzyme that catalyzes the transcription of RNA to DNA. 

Reverse transcription is the copying of an RNA molecule back into its DNA complement. The enzymes that perform this function are called reverse transcriptases. Reverse transcription is used naturally by retroviruses to insert themselves into an organism s genome. Artificially induced reverse transcription is a useful technique for translating unstable messenger RNA (mRNA) molecules into stable cDNA. 

Reverse transcription RNA-directed synthesis of DNA, catalyzed by reverse transcriptase. 

RNA oncogenic vimses have an unusual enzyme, reverse transcriptase, which is capable of making DNA copies from an RNA template. Cells transformed by these retrovimses have been shown to possess DNA transcripts of the viral RNA. It appears that the transformahon from normal to malignant is associated with the acquisition by the cell of viral DNA. 

The nonnucleoside reverse transcriptase inhibitors (NNRTIs), used in the treatment of AIDS, provide interesting examples of clinically relevant noncompetitive inhibitors. The causative agent of AIDS, HIV, belongs to a virus family that relies on an RNA-based genetic system. Replication of the vims requires reverse transcription of the viral genomic RNA into DNA, which is then incorporated into the genome of the infected host cell. Reverse transcription is catalyzed by a virally encoded nucleic acid polymerase, known as reverse transcriptase (RT). This enzyme is critical for viral replication inhibition of HIV RT is therefore an effective mechanism for abrogating infection in patients. 

Mangham DC, Williams A, McMullan DJ, et al. Ewing s sarcoma of bone the detection of specific transcripts in a large, consecutive series of formalin-fixed, decalcified, paraffin-embedded tissue samples using the reverse transcriptase -polymerase chain reaction. Histopathology 2006 48 363-376. 

Thiourea compounds have been observed to inhibit human immunodeficiency virus (HIV) reverse transcriptase, a viral enzyme that is responsible for the reverse transcription of the retroviral RNA to proviral DNA. Phenethylthiazoylthiourea (PETT) compounds were discovered as potent inhibitors of HIV type 1 and display certain structure-activity relationships among various substituents in their structure.199 207 Furthermore, thiourea derivatives have been found to be potent and selective viral inhibitors, antifungal and antibacterial compounds.208 215... 

Up to this point, GIPF expressions have been formulated for only one type of biological activity - the inhibition of reverse transcriptase (RT), the enzyme that promotes the reverse transcription of genomic RNA into double-stranded DNA, a key step in the replication of the human immunodeficiency virus, HIV [82, 87]. Analytical representations were obtained for the anti-HIV potencies of three families of RT inhibitors the correlation coefficients are between 0.930 and 0.952. We are currently investigating the effects of applying the GIPF approach to certain portions of the molecules rather than their entireties. This might reveal the source of the activity, or alternatively, indicate it to be delocalized. 

An amplification reaction that is used to amplify target RNA or denatured DNA is called the transcription-based amplification system (TAS). This technique involves using an enzyme called reverse transcriptase and a primer with sequence complementary to the sample target RNA molecule in order to synthesize a complementary DNA (cDNA) copy of the sample target RNA. After denaturation to separate the strands, another primer and additional reverse transcriptase are added to synthesize a double-stranded cDNA molecule. Since the first primer has also an RNA polymerase binding site, it can, in the presence of T7 RNA polymerase, amplify the double-stranded cDNA to produce 10 to 100 copies of RNA. The cycle of denaturation, synthesis of cDNA, and amplification to produce multiple RNA copies is repeated. With as few as four cycles, a 2- to 5-millionfold amplification of the original sample RNA target is possible. However, the time required to achieve a millionfold amplification is approximately 4 hours, which is the same amount of time required by PCR. The TAS requires, however, the addition of two enzymes at each cycle and, as such, can be cumbersome. 

List of Abbreviations PCR, polymerase chain reaction RT-PCR, reverse transcription polymerase chain reaction DNA, deoxyribonucleic acid RNA, ribonucleic acid RNase, ribonuclease mRNA, messenger RNA GABAa, y-aminobutyric acid type A cRNA, copy RNA dNTPs, deoxy nucleoside triphosphates MMLV, Mouse Moloney murine leukemia vims RT, reverse transcriptase bp, base pair Tm, melting temperature DEPC, diethylpyrocarbonate OD, optical density mL, milliliter SA-PMPs, streptavidin paramagnetic particles dT, deoxy thymidine DTT, dithiothreitol DNase, deoxyribonuclease RNasin, ribonuclease inhibitor UV, ultraviolet TBE, Tris-borate, 1 mM EDTA EDTA, ethylenediaminetetraacetic acid Buffer RET, guanidium thiocyanate lysis buffer PBS, phosphate buffered saline NT2, Ntera 2 neural progenitor cells... 

The life history of a retroviras is described in chapter 17 (see Figure 17.45). A summary is presented here. The genome of a retrovirus is composed of RNA not DNA but, when a retrovirus infects a host cell its RNA is transcribed into DNA, catalysed by the enzyme, reverse transcriptase. This DNA is then incorporated into the genome of the host. On transcription of the host DNA, during cell division, viral mRNA and viral genomic RNA are produced. The... 

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