Reverse transcription
Ahmed YossreTo Dr. Noha Khalifa
Agenda• Introduction• Function in viruses• The process of reverse transcription• Steps of creating viral DNA• How does Integrase enzyme works ?
IntroductionWhat is Reverse transcription ?
The process of DNA transcription but in the opposite direction by the reverse transcriptase.
It was discovered by Howard Temin & David Baltimore at the University of Wisconsin–Madison.
Function in Viruses
• Viruses uses the enzyme to integrate their viral RNA into the host cell
• Some viruses make thier RNA works as a DNA complementary strand
The process of reverse transcription
• The genomes of retroviruses consists of 2 molecules of single strand RNA with a 5’Cap and 3’polyadenylated tail.
• Ex. Of retroviruses:1. HIV virus2. HTLV virus:
The process of creating a double-stranded viral DNA takes place in the cytosol in a series of steps:
Steps of creating a Viral DNA
• Step I:– The tRNA hybridizes to a complementary part
of the viral genome called “Primary Binding site”
• Step II:– The complementary DNA then binds with the
Non-coding regions and the R region of the viral RNA
Steps of creating a Viral DNA
• Step III:– The RNAse H degrades the 5’ end of the RNA
which removes the non-Coding and R regions.
• Step IV:– The Primer starts synthesizing DNA from the
3’ end of the viral genome and adds it to the R-region of the RNA strand
Steps of creating a Viral DNA
• Step V:– The cDNA is extended and the rest of majority
of the viral RNA is degraded• Step VI:
– After synthesizing the complete strand a new strand is being synthesized from the viral RNA
Steps of creating a Viral DNA
• Step VII:– The Primer Binding Site of the first strand then
jumbs to hybrid to the second Primer Binding Site.
• Step VIII:– Both strands are then incorporated and
integrated with the Integrase enzyme
How does Integrase works ?
• 1st : It binds with the nucleus membrane and open a hole into it .
• 2nd : It takes the new viral DNA and go with it into the nucleus.
• With the help of other enzymes it binds the viral DNA with the DNA.
References
• Wikipedia #1• Wikipedia #2• Aids.about.com• Bioproductsmd.com• Google.com
Thank YouAhmed Yossre
Recommended
