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Tat is required for efficient HIV-1 reverse transcription
D Harrich1, C Ulich, L F García-Martínez
1Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235-8594, USA.
The EMBO Journal
|March 17, 1997
Summary
The Tat protein is crucial for efficient human immunodeficiency virus-1 (HIV-1) reverse transcription. Viruses lacking tat show impaired reverse transcription, indicating Tat
Area of Science:
- Virology
- Molecular Biology
- HIV Research
Background:
- Efficient human immunodeficiency virus-1 (HIV-1) reverse transcription depends on tRNA(3)(Lys) binding and reverse transcriptase interaction.
- TAR RNA is essential for efficient HIV-1 reverse transcription.
- The Tat protein regulates HIV-1 gene expression via TAR RNA.
Purpose of the Study:
- To investigate the role of the Tat protein in HIV-1 reverse transcription.
- To determine if Tat influences HIV-1 reverse transcription efficiency.
Main Methods:
- Generated HIV-1 virions lacking the tat gene.
- Infected peripheral blood mononuclear cells (PBMCs) with wild-type and tat-deleted HIV-1.
- Complemented tat-deleted HIV-1 by transfecting tat genes into producer cells.
- Assessed reverse transcription in endogenous assays.
Main Results:
- HIV-1 virions lacking tat exhibited significantly reduced reverse transcription initiation in PBMCs.
- This defect was not attributable to lower levels of genomic RNA, reverse transcriptase, or other viral proteins.
- Tat-deficient HIV-1 reverse transcription defects could be complemented by Tat in producer cells but not in target cells.
- Viruses lacking tat were also defective in endogenous reverse transcription assays despite normal reverse transcriptase levels.
Conclusions:
- The Tat protein plays a critical role in facilitating efficient HIV-1 reverse transcription.
- Tat's function extends beyond regulating gene expression to actively promoting reverse transcription.
- Tat is essential for optimal HIV-1 replication initiation.