If anyone else could not figure out what was going on at 1:00:36 this might help: Hepatitis Delta Virus (HDV) HDV is actually an RNA virus with a circular genome, not a DNA virus. It has a unique life cycle and relies on the hepatitis B virus (HBV) for replication. Delta-Antigen and RNA Editing HDV produces mRNA that encodes a protein called delta-antigen. There are two forms of delta-antigen: small (S-HDAg) and large (L-HDAg). The difference between these two forms is the result of a process called RNA editing. Here's how it works: 1. mRNA Encoding: The HDV's mRNA encodes the delta-antigen with both initiation (start) and termination (stop) codons. The termination codon signals the end of the protein translation. 2. RNA Deaminase Activity: Within the host cells, an enzyme called RNA deaminase (more specifically, adenosine deaminase acting on RNA, or ADAR) can modify the RNA. It changes an adenine (A) base to an inosine (I) within the stop codon. 3. Effect on Translation: Inosine is read as guanosine (G) during translation. This change turns the original stop codon into a tryptophan (W) codon. Instead of stopping translation, the ribosome continues to read the mRNA, extending the protein. 4. Large Delta-Antigen Formation: The change in the codon results in the synthesis of the large delta-antigen (L-HDAg) instead of the small form. A different stop codon downstream is used to terminate the translation of the large delta-antigen. 5. Significance of RNA Editing: This RNA editing process allows the virus to produce two different proteins from the same mRNA sequence. The small and large delta-antigens have different functions in the viral life cycle, and both are essential for the virus's replication and assembly.
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If anyone else could not figure out what was going on at 1:00:36 this might help:
Hepatitis Delta Virus (HDV)
HDV is actually an RNA virus with a circular genome, not a DNA virus. It has a unique life cycle and relies on the hepatitis B virus (HBV) for replication.
Delta-Antigen and RNA Editing
HDV produces mRNA that encodes a protein called delta-antigen. There are two forms of delta-antigen: small (S-HDAg) and large (L-HDAg). The difference between these two forms is the result of a process called RNA editing. Here's how it works:
1. mRNA Encoding: The HDV's mRNA encodes the delta-antigen with both initiation (start) and termination (stop) codons. The termination codon signals the end of the protein translation.
2. RNA Deaminase Activity: Within the host cells, an enzyme called RNA deaminase (more specifically, adenosine deaminase acting on RNA, or ADAR) can modify the RNA. It changes an adenine (A) base to an inosine (I) within the stop codon.
3. Effect on Translation: Inosine is read as guanosine (G) during translation. This change turns the original stop codon into a tryptophan (W) codon. Instead of stopping translation, the ribosome continues to read the mRNA, extending the protein.
4. Large Delta-Antigen Formation: The change in the codon results in the synthesis of the large delta-antigen (L-HDAg) instead of the small form. A different stop codon downstream is used to terminate the translation of the large delta-antigen.
5. Significance of RNA Editing: This RNA editing process allows the virus to produce two different proteins from the same mRNA sequence. The small and large delta-antigens have different functions in the viral life cycle, and both are essential for the virus's replication and assembly.
Sir ! You skipped the translation phase. Kindly summarize the translation of viral mRNA as well.
Every year I try to keep up on these
13:51 I am probably completely wrong here. Could those abortive transcripts, serve as primers themselves to make the polymerase go?
Thanks a ton sir.