Reconstitution of chromatin transcription with purified components reveals a chromatin-specific repressive activity of p300.
Here we describe an in vitro chromatin transcription system in which chromatin assembly and transcription are carried out with purified and defined factors. With basal (also known as general) transcription factors and sequence-specific DNA-binding activators, we observed chromatin-specific, activation domain-dependent transcription. We then examined the biochemical function of purified p300 in the absence of the endogenous factor and other related activities and found, unexpectedly, that p300 has a chromatin-specific, transcriptional repression activity that can be relieved by the addition of acetyl-CoA. This p300-mediated repression is reversible, requires the p300 bromodomain but not the acetyltransferase region, and does not involve the formation of a stable, nuclease-resistant nucleoprotein complex. Hence, the mechanism of transcriptional repression by p300 is distinct from that of histone H1, PARP-1 or Sir2. These findings reveal a novel chromatin-specific repressive function of p300.
Santoso
Buyung
B
Section of Molecular Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0347, USA.
Kadonaga
James T
JT
D000105:Acetyl Coenzyme A / Q000494:pharmacology; D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D002843:Chromatin / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004331:Drosophila melanogaster; D004950:Esterases / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics*; D050880:p300-CBP Transcription Factors / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*
D002843:Chromatin; D012097:Repressor Proteins; D000105:Acetyl Coenzyme A; D000123:Acetyltransferases; D050880:p300-CBP Transcription Factors; D004950:Esterases