Related Experiment Videos
Alternative poly(A) site utilization during adenovirus infection coincides with a decrease in the activity of a
K P Mann1, E A Weiss, J R Nevins
1Section of Genetics, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina.
Abstract:
The recognition and processing of a pre-mRNA to create a poly(A) addition site, a necessary step in mRNA biogenesis, can also be a regulatory event in instances in which the frequency of use of a poly(A) site varies. One such case is found during the course of an adenovirus infection. Five poly(A) sites are utilized within the major late transcription unit to produce more than 20 distinct mRNAs during the late phase of infection. The proximal half of the major late transcription unit is also expressed during the early phase of a viral infection. During this early phase of expression, the L1 poly(A) site is used three times more frequently than the L3 poly(A) site. In contrast, the L3 site is used three times more frequently than the L1 site during the late phase of infection. Recent experiments have suggested that the recognition of the poly(A) site GU-rich downstream element by the CF1 processing factor may be a rate-determining step in poly(A) site selection. We demonstrate that the interaction of CF1 with the L1 poly(A) site is less stable than the interaction of CF1 with the L3 poly(A) site. We also find that there is a substantial decrease in the level of CF1 activity when an adenovirus infection proceeds to the late phase. We suggest that this reduction in CF1 activity, coupled with the relative instability of the interaction with the L1 poly(A) site, contributes to the reduced use of the L1 poly(A) site during the late stage of an adenovirus infection.
Insights
Polyadenylation site selection in adenovirus infection is regulated by the processing factor CF1. Reduced CF1 activity and unstable binding to the L1 poly(A) site during late infection phases explain its decreased utilization.
Area of Science:
- Molecular Biology
- Virology
- Gene Regulation
Background:
- Polyadenylation is a crucial step in mRNA biogenesis, involving the addition of a poly(A) tail to pre-mRNA.
- Poly(A) site usage can be a regulatory mechanism, as observed during adenovirus infections.
- Adenovirus major late transcription unit exhibits differential poly(A) site usage between early and late infection phases.
Purpose of the Study:
- To investigate the role of the CF1 processing factor in regulating poly(A) site selection during adenovirus infection.
- To determine the molecular basis for the differential usage of L1 and L3 poly(A) sites in adenovirus.
Main Methods:
- Comparative analysis of CF1 binding stability to L1 and L3 poly(A) sites.
- Assay of CF1 activity levels during different stages of adenovirus infection.
Main Results:
- The interaction of CF1 with the L1 poly(A) site is less stable compared to the L3 poly(A) site.
- A significant decrease in CF1 activity is observed as adenovirus infection progresses to the late phase.
- These findings correlate with the reduced utilization of the L1 poly(A) site during late-stage infection.
Conclusions:
- Reduced CF1 activity and less stable CF1-L1 poly(A) site interaction contribute to the decreased use of the L1 poly(A) site in late-stage adenovirus infection.
- Poly(A) site selection is a key regulatory point influenced by processing factor dynamics during viral replication.