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Human immunodeficiency virus type 2 long terminal repeat: analysis of regulatory elements
1Laboratory of Tumor Cell Biology, National Cancer Institute, Bethesda, MD 20892.
Summary
The human immunodeficiency virus type 2 (HIV-2) tat gene product requires two subelements in its response element for optimal transactivation, unlike HIV-1. This difference explains why HIV-2 tat poorly transactivates HIV-1 gene expression.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Human immunodeficiency virus type 2 (HIV-2) and simian immunodeficiency virus (SIVmac) share regulatory elements within their long terminal repeats (LTRs).
- The tat gene product plays a crucial role in regulating viral gene expression through interaction with specific LTR elements.
Purpose of the Study:
- To investigate the structural and functional differences in the tat response elements of HIV-2 and HIV-1.
- To elucidate the mechanism by which HIV-2 tat gene product mediates transactivation and affects other regulatory elements.
Main Methods:
- Comparative analysis of HIV-2 and HIV-1 LTR sequences, focusing on tat response elements.
- Functional assays to assess transactivation by HIV-2 and HIV-1 tat gene products in different cellular contexts.
Main Results:
- HIV-2 LTR contains a complex tat response element with two essential subelements for HIV-2 tat transactivation.
- HIV-1 tat gene product can utilize only one of these subelements, explaining its inefficiency with the HIV-2 LTR.
- HIV-2 tat gene product also influences upstream regulatory elements, including enhancer activity.
Conclusions:
- Structural variations in tat response elements contribute to differential transactivation efficiency between HIV-2 and HIV-1.
- Transcriptional modulation by tat gene products is a key mechanism in regulating HIV-2 and SIVmac gene expression.