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A reverse transcriptase (RT) is an enzyme used to convert RNA genome to DNA, a process termed reverse transcription.Reverse transcriptases are used by viruses such as HIV, COVID-19, and hepatitis B to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, and by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes.
All members of Riboviria contain a gene that encodes for an RNA-dependent polymerase, also called RNA-directed polymerase. There are two types of RNA-dependent polymerases: RNA-dependent RNA polymerase (RdRp), also called RNA replicase, which synthesizes RNA from RNA, and RNA-dependent DNA polymerase (RdDp), also called reverse transcriptase (RT), which synthesizes DNA from RNA. [3]
Revtraviricetes is a class of viruses that contains all viruses that encode a reverse transcriptase. [1] The group includes all ssRNA-RT viruses (including the retroviruses) and dsDNA-RT viruses. It is the sole class in the phylum Artverviricota, which is the sole phylum in the kingdom Pararnavirae. [2]
These proteins are typically involved in the early stages of genome replication, and include reverse transcriptase and integrase. Reverse transcriptase is the virally encoded RNA-dependent DNA polymerase. The enzyme uses the viral RNA genome as a template for the synthesis of a complementary DNA copy. Reverse transcriptase possesses [RNase H ...
Through reverse transcription, retrotransposons amplify themselves quickly to become abundant in eukaryotic genomes such as maize (49–78%) [3] and humans (42%). [4] They are only present in eukaryotes but share features with retroviruses such as HIV, for example, discontinuous reverse transcriptase-mediated extrachromosomal recombination. [5] [6]
A retrovirus is a type of virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. [2] After invading a host cell's cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern, thus retro (backward).
The evolution of HBV in humans was shown to reflect known events of human history such as the first peopling of the Americas during the late Pleistocene and the Neolithic transition in Europe. [120] Ancient DNA studies have also showed that some ancient hepatitis viral strains still infect humans, while other strains became extinct.
Telomerase reverse transcriptase (abbreviated to TERT, or hTERT in humans) is a catalytic subunit of the enzyme telomerase, which, together with the telomerase RNA component (TERC), comprises the most important unit of the telomerase complex. [5] [6] Telomerases are part of a distinct subgroup of RNA-dependent polymerases.