A cofactor, TIP30, specifically enhances HIV-1 Tat-activated transcription.
Replication of HIV-1 requires the viral Tat protein, which increases the extent of transcription elongation by RNA polymerase II after activation at the single viral long terminal repeat (LTR) promoter. This effect of Tat on transcription requires Tat interactions with a 5' region (TAR) in nascent transcripts as well as Tat-specific cofactors. The present study identifies a cellular protein, TIP30, that interacts with Tat and with an SRB-containing RNA polymerase II complex both in vivo and in vitro. Coexpression of TIP30 specifically enhances transactivation by Tat in transfected cells, and immunodepletion of TIP30 from nuclear extracts abolishes Tat-activated transcription without affecting Tat-independent transcription. These results implicate TIP30 as a specific coactivator that may enhance formation of a Tat-RNA polymerase II holoenzyme complex.
Xiao
H
H
Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY 10021, USA.
Tao
Y
Y
Greenblatt
J
J
Roeder
R G
RG
D000123:Acetyltransferases; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002628:Chemoreceptor Cells; D002846:Chromatography, Affinity; D029968:Escherichia coli Proteins; D015696:Gene Products, tat / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014779:Virus Replication; D054322:tat Gene Products, Human Immunodeficiency Virus
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D015696:Gene Products, tat; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C057331:Tar protein, E coli; D014157:Transcription Factors; D054322:tat Gene Products, Human Immunodeficiency Virus; D000123:Acetyltransferases; C111246:HTATIP2 protein, human