The histone chaperone TAF-I/SET/INHAT is required for transcription in vitro of chromatin templates.
To uncover factors required for transcription by RNA polymerase II on chromatin, we fractionated a mammalian cell nuclear extract. We identified the histone chaperone TAF-I (also known as INHAT [inhibitor of histone acetyltransferase]), which was previously proposed to repress transcription, as a potent activator of chromatin transcription responsive to the vitamin D3 receptor or to Gal4-VP16. TAF-I associates with chromatin in vitro and can substitute for the related protein NAP-1 in assembling chromatin onto cloned DNA templates in cooperation with the remodeling enzyme ATP-dependent chromatin assembly factor (ACF). The chromatin assembly and transcriptional activation functions are distinct, however, and can be dissociated temporally. Efficient transcription of chromatin assembled with TAF-I still requires the presence of TAF-I during the polymerization reaction. Conversely, TAF-I cannot stimulate transcript elongation when added after the other factors necessary for assembly of a preinitiation complex on naked DNA. Thus, TAF-I is required to facilitate transcription at a step after chromatin assembly but before transcript elongation.
Gamble
Matthew J
MJ
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021, USA.
Erdjument-Bromage
Hediye
H
Tempst
Paul
P
Freedman
Leonard P
LP
Fisher
Robert P
RP
D002458:Cell Fractionation; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006367:HeLa Cells; D056488:Histone Chaperones; D006801:Humans; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013698:Templates, Genetic; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C070633:Gal-VP16; D056488:Histone Chaperones; D018832:Molecular Chaperones; D018167:Receptors, Calcitriol; D011993:Recombinant Fusion Proteins; C513473:SET protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D012319:RNA Polymerase II