Reverse transcriptase (RT) is an enzyme that is useful for generating cDNA or complementary DNA from the template of RNA. This process is called reverse transcription. Viruses like hepatitis B and HIV use reverse transcriptases for replicating their genomes by some retrotransposon and mobile genetic components. This is done for proliferating in the host genome. Contrary to relief, this process doesn’t violate the flow of some genetic info as the classical central dogma described transfers of info to DNA from RNA possible.
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Retroviral RT Has Got Three Chronological biochemical activities, and they are:
RNA-dependent DNA polymerase activity
DNA-dependent DNA polymerase activity
These activities permit the enzyme to change into double-stranded cDNA from single-stranded DNA. In retrotransposons and retroviruses, this cDNA can combine with a host genome, and from here, novice RNA imitations can be made through host-cell transcription. This same process of reaction is hugely utilized in a laboratory for converting DNA from RNA for use in molecular cloning, PCR or polymerase chain reaction, RNA sequencing, or genome analysis.
When people wish to know what is reverse transcriptase, they must know that it is an enzyme whose job is synthesizing DNA utilizing RNA in the form of a template. It was discovered by David Baltimore and Howard Temin in the year 1970. The enzyme started from being a paradigm-busting event to some standard item that is included in the toolkit of molecular biology and that too in a record time. This turned invaluable to form DNA probes that are complementary to the messenger RNA.
Some viruses, like hepatitis B virus and HIV, employ reverse transcriptase enzymes, and the viruses use these enzymes for copying their genome, and it permits them to get into and also proliferate within the host cells. When the matter comes to eukaryotic cells, then the reverse transcriptase enzymes get used for extending the telomeres towards the finishing of a linear chromosome.
A reverse transcribing DNA virus, like hepadnavirus, allows RNA to work in the form of a template to form a DNA strand. And so, it can be concluded that this enzyme permits the viruses to contaminate the host cell. In the absence of reverse transcriptase, the viral genome won’t be capable of entering as well as copying within the host cell.
Reverse transcription occurs in both eukaryotes and prokaryotes, and it is considered the synthesis from an RNA template to DNA. Retroviruses get classed through the presence of a reverse transcriptase that is RNA-dependent DNA polymerase. The virus which causes HIV (Human Immunodeficiency Virus) and AIDS are considered retrovirus. As nuclear cell division does not utilize reverse transcriptase, the highly useful anti-HIV drugs do target reverse transcriptase. Telomerase is considered a particular reverse transcriptase enzyme.
The process of reverse transcription starts when a viral particle gets into a target cell’s cytoplasm. The RNA genome gets into the cytoplasm in the form of a nucleoprotein complex, and this hasn’t been characterized till now. The method of reverse transcription does generate through some intricate sequence of steps. This DNA happens to be collinear with the template of RNA though it comprises some terminal duplications known as the LTRs (long terminal repeats). They do not remain present in the viral RNA. Some extant models meant for reverse transcription provide a couple of specialized template switches, and they are called strand-transfer reactions for generating the LTRs.
HIV is considered a retrovirus, and it is meant to carry a single-stranded RNA in the form of its genetic component in place of the double-stranded DNA that human cells carry. Again, retroviruses, too, have got the reverse enzyme transcriptase. With its help, the copying of RNA is done into DNA, and it uses the DNA imitation for infecting the host cells as well as humans. If HIV does infect a cell, then the first thing it does is it attaches with the host cell and fuse it. After this, the RNA gets changed into DNA. The virus utilizes the machinery of the host cell for copying itself at the time of reverse transcription. The novice HIV copies do not remain with the host cell as they begin to infect other cells.
Q.1 What is called a polymerase?
Ans: A polymerase is acknowledged as an enzyme, and it synthesizes long chains of nucleic acids or polymers. RNA polymerase and DNA polymerase are utilized for assembling RNA and DNA molecules. They do this job by imitating a template of DNA utilizing base-pairing interactions through half ladder imitation. A DNA polymerase that emerges from Thermus aquaticus, the thermophilic bacterium, is utilized in a polymerase chain reaction, and it has turned into a vital process of molecular biology. Polymerases can be template-independent or template-dependent. Poly-A-polymerase is considered an instance of template-independent polymerase, whereas Terminal deoxynucleotidyl transferase continues both template-dependent and template-independent activities.
Q.2 What is the difference between reverse transcriptase and DNA polymerase?
Ans: Reverse transcriptase is DNA-dependent RNA polymerase, and it is considered the imitated enzyme of retroviruses. Nonetheless, cellular DNA polymerases utilize DNA in the form of a template to make novice DNAs but reverse transcriptase function to utilize only the single-stranded RNA to synthesize viral DNA. It is a pretty unusual process to make DNA from RNA, and it is known as reverse transcription. It is given this name as it reverses the flow of genetic info “to RNA from DNA” in place of “to DNA from RNA” that is found in transcription. As reverse transcriptase is important for some retroviruses, like HIV-1, it becomes the target of countless antiretroviral therapeutics.
Q.3 What are the uses of reverse transcriptases?
Ans: RTS are hugely utilized in biotechnology for their capability of synthesizing DNA utilizing the templates of RNA. The progressions were made familiar during the late 1990s. The generation-next sequencing methods and cDNA microarrays have opened many fresh chances to identify all the RNA molecules in just one cell. RTS is also vital behind the engineered RT variants and wild-type variants of some viruses, like AMV (avian myeloblastosis virus), MLV (murine leukaemia virus), Geobacillus stearothermophilus group II introns, and HIV-1. They have been formed into highly efficient tools for studying gene expression as they augment processivity, catalytic efficiency, and thermostability of DNA synthesis.