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Extensive interactions between HIV TAT and TAF(II)250
J D Weissman1, J R Hwang, D S Singer
1Experimental Immunology Branch, NCI, NIH, 9000 Rockville Pike, Bethesda, MD 20892, USA. jw35s@nih.gov
Biochimica Et Biophysica Acta
|March 21, 2001
Summary
The HIV Tat protein represses transcription by binding TFIID
Area of Science:
- Molecular Biology
- Virology
- Gene Regulation
Background:
- The HIV transactivator protein, Tat, is known to repress transcription initiation.
- This repression is mediated by Tat's C-terminal segment binding to TFIID component TAF(II)250.
- Previous studies had not precisely defined the interaction sites between Tat and TAF(II)250.
Purpose of the Study:
- To precisely map the interaction sites between the HIV Tat protein and TFIID component TAF(II)250.
- To elucidate the domains of Tat and TAF(II)250 involved in their interaction.
- To understand the role of TAF(II)250 in Tat-mediated transcriptional repression.
Main Methods:
- Protein interaction mapping using various Tat and TAF(II)250 domains.
- Analysis of Tat domains (N-terminal, C-terminal, cysteine-rich, acidic, glutamine-rich) and TAF(II)250 segments.
- Assessing the requirement of functional TAF(II)250 for Tat-mediated repression.
Main Results:
- Extensive interactions involving multiple contacts between Tat and TAF(II)250 were identified.
- Tat's C-terminal domain binds TAF(II)250's acetyl transferase (AT) domain (885-1034 aa).
- Tat's N-terminal domain binds discontinuous TAF(II)250 segments (885-984 aa and 1120-1279 aa), involving specific Tat domains.
Conclusions:
- Tat interacts extensively with TAF(II)250 through distinct domains.
- Functional TAF(II)250 is required for Tat-mediated repression of transcription initiation.
- HIV LTR transcription's independence from TAF(II)250 may explain its resistance to Tat-mediated repression.