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Human immunodeficiency virus type 1 and 2 Tat proteins specifically interact with RNA polymerase II
G Mavankal1, S H Ignatius Ou, H Oliver
1Division of Molecular Virology, University of Texas Southwestern Medical Center, Dallas 75235-8594, USA.
Summary
Human immunodeficiency virus (HIV) transactivator protein Tat directly interacts with RNA polymerase II, enhancing viral gene expression. This interaction, mediated by Tat's basic domain, targets the largest subunit of RNA polymerase II.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- The Tat-responsive region (TAR) is crucial for human immunodeficiency virus (HIV) gene expression activation by the transactivator protein Tat.
- Previous studies showed RNA polymerase II binds TAR RNA, and Tat inhibits this binding, suggesting direct Tat-RNA polymerase II interactions.
Purpose of the Study:
- To investigate direct protein-protein interactions between HIV Tat and RNA polymerase II.
- To identify the domains of Tat and subunits of RNA polymerase II involved in this interaction.
Main Methods:
- Gel-retardation analysis to study RNA polymerase II-TAR RNA binding.
- Protein interaction studies using HIV-1 and HIV-2 Tat proteins with RNA polymerase II.
- Mutagenesis of Tat proteins to identify interaction domains.
- "Far Western" analysis to pinpoint the interacting subunit of RNA polymerase II.
Main Results:
- Both HIV-1 and HIV-2 Tat proteins specifically interact with RNA polymerase II.
- The basic domains of both HIV-1 and HIV-2 Tat are essential for this interaction.
- The largest subunit of RNA polymerase II appears to be the primary site of Tat interaction.
Conclusions:
- RNA polymerase II is a direct cellular target of HIV Tat.
- Tat-mediated interaction with RNA polymerase II contributes to increased transcriptional elongation from the HIV long terminal repeat.
- This interaction mechanism is conserved between HIV-1 and HIV-2.