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Identification of cis-acting repressor activity within human immunodeficiency virus type 1 protease sequences
1Department of Microbiology and Immunology, Medical University of South Carolina, Charleston 29425-2230, USA.
Virology
|August 4, 1997
Summary
The human immunodeficiency virus type-1 (HIV-1) Rev protein enhances viral gene expression by overcoming negative elements. This study reveals novel cis-acting repressor sequences within HIV-1 protease that affect RNA stability.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Human immunodeficiency virus type-1 (HIV-1) encodes regulatory proteins, including Rev, essential for viral replication.
- Rev protein facilitates the expression of unspliced and partially spliced viral RNAs by interacting with the Rev response element (RRE).
- Negative regulatory elements within viral RNAs can impede gene expression, and understanding their function is crucial for viral control.
Purpose of the Study:
- To investigate the effect of the HIV-1 Rev protein on the expression of HIV-1 protease (PR)-containing constructs.
- To identify and characterize cis-acting repressor sequences (CRS) within HIV-1 PR and other viral RNA elements.
- To elucidate the mechanism by which Rev influences viral RNA accumulation and protein expression.
Main Methods:
- Transient transfection of COS cells with HIV-1 PR-containing constructs.
- Analysis of proteolytic activity and RNA expression levels in the presence and absence of Rev.
- Assessment of CRS activity within different viral RNA sequences, including PR, RRE, nef, and LTR.
Main Results:
- Rev significantly increased proteolytic activity and cytoplasmic RNA accumulation of PR-containing constructs.
- Rev enhanced the total RNA production from PR-containing constructs, indicating the presence of CRS.
- PR sequences exhibited CRS activity in both sense and antisense orientations, suggesting a novel mechanism of RNA regulation.
- RRE sequences showed a minor CRS effect, and additional CRS activity was found in unspliced RNA containing nef and LTR.
Conclusions:
- HIV-1 protease contains a novel cis-acting repressor sequence that functions independently of its orientation.
- This PR-mediated CRS activity appears to regulate RNA stability at the cytoplasmic or nuclear level.
- Rev protein plays a critical role in overcoming these negative regulatory elements to promote viral gene expression.