Ahmed Yossre To Dr. Noha Khalifa

Introduction Function in viruses The process of reverse transcription Steps of creating viral DNA How does Integrase enzyme works ?

Introduction

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 virus 2.HTLV virus: The process of creating a double-stranded viral DNA takes place in the cytosol in a series of steps:

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

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

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

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 ? 1 st : It binds with the nucleus membrane and open a hole into it. 2 nd : 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