Download Reverse Transcriptase -- (RNA

Reverse Transcriptase -- (RNA-dependent DNA Polymerase)
Crystallographic structure of reverse transcriptase
In the fields of molecular biology and biochemistry, a reverse transcriptase, also known
as RNA dependent DNA polymerase, is a DNA polymerase enzyme that transcribes
single stranded RNA into double-stranded DNA. It also helps in the formation of a
double helix DNA once the RNA has been reverse transcribed into a single strand cDNA.
Normal transcription involves the synthesis of RNA from DNA; hence, reverse
transcription is the reverse of this.
The enzyme is encoded and used by reverse-transcribing viruses, which use the enzyme
during the process of replication. Reverse-transcribing RNA viruses, such as
retroviruses, use the enzyme to reverse-transcribe their RNA genomes into DNA, which
is then integrated into the host genome and replicated along with it.
HIV infects humans with the use of this enzyme. Without reverse transcriptase, the viral
genome would not be able to incorporate into the host cell, resulting in the failure of
the ability to replicate.
Reverse transcriptase creates single stranded DNA from an RNA template.
The process of reverse transcription is extremely error-prone and it is during this
step that mutations may occur. Such mutations may cause drug resistance
As HIV uses reverse transcriptase to copy its genetic material and generate new
viruses (part of a retrovirus proliferation circle), specific drugs have been designed to
disrupt the process and thereby suppress its growth. Collectively, these drugs are known
as reverse transcriptase inhibitors.
Reverse transcriptase is commonly used in research to apply the polymerase
chain reaction technique to RNA in a technique called reverse transcription
polymerase chain reaction (RT-PCR). The classical PCR technique can be
applied only to DNA strands, but, with the help of reverse transcriptase, RNA
can be transcribed into DNA, thus making PCR analysis of RNA molecules
possible. Reverse transcriptase is used also to create cDNA libraries from
mRNA. The commercial availability of reverse transcriptase allows scientists to
clone, sequence, and characterize DNA.
Reverse transcriptase has also been employed in insulin production. By
Inserting eukaryotic mRNA for insulin production along with reverse
transcriptase into bacteria, the mRNA can insert itself into the bacteria’s
genome, and large amounts of insulin can be created, decreasing the need to
harvest pig pancreas and other such traditional sources. Inserting eukaryotic
DNA (instead of mRNA) into Bacteria would not work because it is fragmented,
with introns, and would not transcribe successfully using the bacteria's
ribosome.
Quiz – Reverse Transcriptase
1) What is a reverse transcriptase?
a) A DNA dependent polymerase
b) A RNA –dependent DNA polymerase
c) A RNA dependent Polymerase
d) A virus reverses the transcription process
2) A reverse transcriptase is a (an)
a)
b)
c)
d)
Protein
Virus
Nucleic acid
Fatty acid
3) A reverse transcriptase has how many subunits?
a)
b)
c)
d)
One
Two
Three
Four
4) The function of the reverse transcriptase is to
a)
b)
c)
d)
To transcribe complimentary strand DNA into RNA.
To cleave the double strand DNA into single strand DNA.
To transcribe single strand RNA into double stranded DNA.
To make copies of more single strand RNA.
5) The reverse transcriptase is used during the process of:
a)
b)
c)
d)
Replication
Translation
Encoding
Cell division
Challenge Question
If you are a scientist and want to develop a
drug to inhibit viral infection, what do you
need to know to accomplish this mission?
Answers – Reverse Transcriptase
1)
2)
3)
4)
5)
b
a
b
c
c
Answer to the challenge question
Answer may vary between students. The
main idea is that students need to
understand the pathway how the virus infect
the host cell, what enzymes are required in
the process and what drugs can be developed
to prevent the enzymes formation, thus
prevent the lifecycle of the virus to continue.