Reverse transcriptase
Enzyme that synthesizes DNA from an RNA template.
Reverse transcriptase is an enzyme that builds a DNA strand using an RNA molecule as a guide, a process called reverse transcription. This enzyme is employed by viruses like HIV and hepatitis B to copy their genomes, by retrotransposons to multiply within a host’s DNA, and by eukaryotic cells to lengthen the telomeres on chromosome ends. Rather than breaking the central dogma of genetics, this process expands it by allowing information to flow from RNA back to DNA.
Retroviral reverse transcriptase carries out three sequential chemical tasks: copying RNA into DNA, breaking down RNA in RNA-DNA hybrids, and copying single-stranded DNA into double-stranded DNA. Together, these steps turn single-stranded RNA into double-stranded cDNA. In retroviruses and retrotransposons, this cDNA can be inserted into the host genome, where the host cell’s machinery then makes new RNA copies. In laboratories, the same reaction is widely used to convert RNA into DNA for cloning, sequencing, PCR, or genome analysis.
**History** Reverse transcriptase was discovered by Howard Temin at the University of Wisconsin–Madison in Rous sarcoma virus particles and independently isolated by David Baltimore in 1970 at MIT from two RNA tumor viruses: murine leukemia virus and again Rous sarcoma virus. They shared the 1975 Nobel Prize in Physiology or Medicine with Renato Dulbecco. The enzyme was first called RNA-dependent DNA polymerase. The name “reverse transcriptase” came from an anonymous letter to *Nature*, appearing as early as August 1970.
Well-studied reverse transcriptases include: - HIV-1 reverse transcriptase, from human immunodeficiency virus type 1, with two subunits of 66 and 51 kilodaltons. - M-MLV reverse transcriptase from Moloney murine leukemia virus, a single 75 kDa monomer. - AMV reverse transcriptase from avian myeloblastosis virus, with two subunits of 63 kDa and 95 kDa. - Telomerase reverse transcriptase, which maintains eukaryotic chromosome telomeres. - Defense-associated reverse transcriptase (DRT) ribonucleoprotein complexes, a class of prokaryotic antiviral systems made of reverse transcriptase enzymes and associated non-coding RNAs. These complexes help bacteria and archaea defend against bacteriophage infection by synthesizing nucleic acids.
**Function in viruses** Viruses that rely on reverse transcription as a replication step encode and use these enzymes. R
- discovered_by
- Howard Temin and David Baltimore
- year_discovered
- 1970
- field
- Molecular biology, virology
- known_for
- Reverse transcription of RNA to DNA
- nobel_prize
- 1975 Nobel Prize in Physiology or Medicine (shared with Renato Dulbecco)
Quick Facts
- Symbol
- RVT_1
- Pfam
- PF00078
- Pfam Clan
- CL0027
- Interpro
- IPR000477
- Prosite
- PS50878
- Scop
- 1hmv
- Cdd
- cd00304
Facts from the source article.
Lore & Background
Reverse transcriptases were discovered by Howard Temin at the University of Wisconsin–Madison in Rous sarcoma virions and independently isolated by David Baltimore in 1970 at MIT from two RNA tumour viruses: murine leukemia virus and again Rous sarcoma virus. For their achievements, they shared the 1975 Nobel Prize in Physiology or Medicine (with Renato Dulbecco). Reverse transcriptase was initially called RNA-dependent DNA polymerase. The term 'reverse transcriptase' was coined in an anonymous letter to Nature, where it appeared as early as August 1970.
Well-studied reverse transcriptases include HIV-1 reverse transcriptase, from human immunodeficiency virus type 1, which has two subunits with respective molecular weights of 66 and 51 kDas; M-MLV reverse transcriptase from the Moloney murine leukemia virus, a single 75 kDa monomer; AMV reverse transcriptase from the avian myeloblastosis virus, also with two subunits (63 kDa and 95 kDa); telomerase reverse transcriptase that maintains the telomeres of eukaryotic chromosomes; and defense-associated reverse transcriptase (DRT) ribonucleoprotein complexes, a class of prokaryotic antiviral systems.
Reader's Guide
Reverse transcriptase is central to the replication of retroviruses such as HIV, enabling the conversion of viral RNA into double-stranded DNA that integrates into the host genome. This enzyme's three sequential biochemical activities—RNA-dependent DNA polymerase, ribonuclease H, and DNA-dependent DNA polymerase—allow it to convert single-stranded RNA into double-stranded cDNA. The same reactions are widely used in the laboratory for molecular cloning, RNA sequencing, polymerase chain reaction (PCR), and genome analysis. The process of reverse transcription is extremely error-prone, leading to mutations that may cause drug resistance. In cellular life, retrotransposons and telomerase also utilize reverse transcriptase, and in prokaryotes, bacterial Retrons code for reverse transcriptase used in msDNA synthesis. The discovery expanded the classical central dogma of molecular biology.
Did You Know?
- Reverse transcriptase was initially called RNA-dependent DNA polymerase.
- The term 'reverse transcriptase' was coined in an anonymous letter to Nature in August 1970.
- HIV-1 reverse transcriptase has two subunits with molecular weights of 66 and 51 kDas.
- Defense-associated reverse transcriptase (DRT) complexes are prokaryotic antiviral systems against bacteriophage infection.
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