Reverse transcriptase
Virology · Molecular Biology · Biotechnology
Say it: rih-VURS tran-SKRIP-tays
Reverse transcriptase is an enzyme that builds DNA from an RNA template, letting retroviruses such as HIV turn their RNA genome into DNA.
Also: RNA-directed DNA polymerase, RNA-dependent DNA polymerase
Definition
What is reverse transcriptase?
Reverse transcriptase is a DNA polymerase that uses RNA, rather than DNA, as its template. It runs the usual flow of genetic information backward, from RNA to DNA, which is how it got its name. Retroviruses such as HIV carry the enzyme inside their capsid, and related enzymes occur in some other viruses and in mobile genetic elements.
HIV reverse transcriptase does three jobs. It first builds a strand of complementary DNA, or cDNA, along the viral RNA. A second active site then chops up the RNA strand, and the enzyme finally builds a matching second DNA strand, producing a double-stranded copy that can be inserted into the host's chromosomes. The enzyme makes frequent copying errors, so HIV mutates quickly and can evolve resistance to drugs within weeks. Because the viral enzyme differs from the cell's own polymerases, it is a major drug target: nucleoside analogs such as AZT stop the growing DNA chain, and other drugs bind next to the active site and distort it.
Reverse transcriptase was discovered in 1970 by Howard Temin and David Baltimore. In the lab it is used to copy messenger RNA into cDNA, the first step of RT-PCR and of RNA sequencing.
Word parts
Where does the term “reverse transcriptase” come from?
- reverse
- turned backLatin reversus
- transcript-
- copied outLatin transcribere, from trans- (across) + scribere (to write)
- -ase
- enzymefrom diastase, Greek diastasis, separation
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Terms that go with it
- RetrovirusA retrovirus is an RNA virus that copies its genome into DNA with reverse transcriptase and inserts that DNA into the host cell's chromosomes.
- DNA polymeraseDNA polymerase is an enzyme that builds new DNA by adding nucleotides one at a time to a growing strand, using an existing strand as a template.
- RNARNA is a usually single-stranded nucleic acid, built with the sugar ribose and the base uracil, that carries and uses genetic information to make proteins.
- TranscriptionTranscription is the process in which a cell copies the DNA sequence of a gene into a matching strand of RNA.
- Polymerase chain reactionThe polymerase chain reaction (PCR) is a lab technique that copies one chosen stretch of DNA over and over until there are billions of copies.
- RNA sequencingRNA sequencing (RNA-seq) is a method that uses high-throughput sequencing to identify and count the RNA molecules in a sample.
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Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Microbiology, 6.2 The Viral Life Cycle
- RCSB PDB-101 Molecule of the Month: HIV Reverse Transcriptase
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