Transcriptional synergy between Tat and PCAF is dependent on the binding of acetylated Tat to the PCAF bromodomain.
The human immunodeficiency virus (HIV) Tat protein plays an essential role in promoting efficient transcriptional elongation of viral transcripts. We report that the transcriptional co-activator PCAF and Tat interact and synergize to activate the HIV promoter. The binding of Tat and PCAF in vitro and in vivo is dependent on the acetylated state of Lys50 of Tat and on the PCAF bromodomain. Structural analysis of the acetylated Tat peptide bound to the PCAF bromodomain defined amino acids Y47 and R53 in Tat and V763, Y802, and Y809 in PCAF as critical interaction points between the two proteins. Mutation of each of these residues in either Tat or PCAF inhibited in a cumulative manner the Tat-PCAF interaction in vitro and in vivo, and abrogated the synergistic activation of the HIV promoter by both proteins. These observations demonstrate that acetylation of Tat establishes a novel protein-protein interaction domain at the surface of Tat that is necessary for the transcriptional activation of the HIV promoter.
Dorr
Alexander
A
Deutsches Krebsforschungszentrum (DKFZ), 69120 Heidelberg, D-10115 Berlin, Germany,
Kiermer
Veronique
V
Pedal
Angelika
A
Rackwitz
Hans-Richard
HR
Henklein
Peter
P
Schubert
Ulrich
U
Zhou
Ming-Ming
MM
Verdin
Eric
E
Ott
Melanie
M
D000123:Acetyltransferases / Q000737:chemistry / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D015696:Gene Products, tat / Q000737:chemistry / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D051548:Histone Acetyltransferases; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008164:Luminescent Proteins; D008239:Lysine / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D015696:Gene Products, tat; D008164:Luminescent Proteins; D010455:Peptides; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D008156:Luciferases; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; D008239:Lysine