title: Histone acetyltransferases regulate HIV-1 enhancer activity in vitro.
abstract: Specific inhibitors of histone deacetylase, such as trichostatin A (TSA) and trapoxin (TPX), are potent inducers of HIV-1 transcription in latently infected T-cell lines. Activation of the integrated HIV-1 promoter is accompanied by the loss or rearrangement of a positioned nucleosome (nuc-1) near the viral RNA start site. Here we show that TSA strongly induces HIV-1 transcription on chromatin in vitro, concomitant with an enhancer factor-assisted increase in the level of acetylated histone H4. TSA treatment, however, did not detectably alter enhancer factor binding or the positioning of nuc-1 on the majority of the chromatin templates indicating that protein acetylation and chromatin remodeling may be limiting steps that occur only on transcriptionally competent templates, or that remodeling of nuc-1 requires additional factors. To assess the number of active chromatin templates in vitro, transcription was limited to a single round with low levels of the detergent Sarkosyl. Remarkably, HIV-1 transcription on chromatin was found to arise from a small number of active templates that can each support nearly 100 rounds of transcription, and TSA increased the number of active templates in each round. In contrast, transcription on naked DNA was limited to only a few rounds and was not responsive to TSA. We conclude that HIV-1 enhancer complexes greatly facilitate transcription reinitiation on chromatin in vitro, and act at a limiting step to promote the acetylation of histones or other transcription factors required for HIV-1 enhancer activity.
authors.affiliation: The Salk Institute for Biological Studies, La Jolla, California 92037-1099, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Sheridan
authors.forename: T P
authors.initials: TP
authors.lastname: Mayall
authors.forename: E
authors.initials: E
authors.lastname: Verdin
authors.forename: K A
authors.initials: KA
authors.lastname: Jones
mesh_terms: D000123:Acetyltransferases / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002474:Cell-Free System; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D016322:HIV Enhancer; D015497:HIV-1 / Q000235:genetics*; D051548:Histone Acetyltransferases; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D051821:Lymphoid Enhancer-Binding Factor 1; D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D002843:Chromatin; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D051821:Lymphoid Enhancer-Binding Factor 1; C079787:NUC-1 protein, Neurospora crassa; D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C085968:UBP1 protein, human; C067070:trapoxin A; C012589:trichostatin A; C090528:DNA modification methylase HindIII; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C074326:CTTAAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific; D006655:Histone Deacetylases