The coactivators CBP/p300 and the histone chaperone NAP1 promote transcription-independent nucleosome eviction at the HTLV-1 promoter

Abstract

The human T cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T cell leukemia/lymphoma. The multifunctional virally encoded oncoprotein Tax is responsible for malignant transformation and potent activation of HTLV-1 transcription. Tax, in complex with phosphorylated cAMP response element binding protein (pCREB), strongly recruits the cellular coactivators CREB binding protein (CBP)/p300 to the viral promoter concomitant with transcriptional activation. Although the mechanism of activator/coactivator-mediated transcriptional activation is poorly understood, the recruitment of CBP/p300 by regulatory factors appears to function, in part, by promoting changes in chromatin architecture that are permissive to transcriptional activation. Here, we show that CBP/p300 recruitment promotes histone acetylation and eviction of the histone octamer from the chromatin-assembled HTLV-1 promoter template in vitro. Nucleosome disassembly is strictly acetyl-CoA dependent and is not linked to ATP utilization. We find that the histone chaperone, nucleosome assembly protein 1 (NAP1), cooperates with CBP/p300 in eviction of the acetylated histones from the chromatin template. These findings reveal a unique mechanism in which the DNA-bound Tax/pCREB complex recruits CBP/p300, and together with NAP1, the coactivators cooperate to dramatically reduce nucleosome occupancy at the viral promoter in an acetylation-dependent and transcription-independent fashion.Tax ͉ cAMP response element binding protein ͉ acetylation ͉ chromatin ͉ histone acetyltransferase

Transcription Factor–Dependent Chromatin Remodeling at Heat Shock and Copper-Responsive Promoters in Chlamydomonas reinhardtii

“…Our data agree very well with observations made at the yeast HSP82 promoter: there, nucleosome occupancy declines drastically within the first 60 s after onset of heat stress and is preceded by a burst of acetylation of histones H2A, H3, and H4 (Zhao et al, 2005). A correlation between histone acetylation and nucleosome loss was demonstrated previously also at the yeast PHO5, SSA4, and HSP12 promoters (Reinke and Hö rz, 2003;Erkina and Erkine, 2006), at the viral HTLV-1 promoter in human cells (Sharma and Nyborg, 2008), or at the Arabidopsis thaliana HSP18.2 promoter (Kodama et al, 2007).…”

Structural evidence for Nap1‐dependent H2A–H2B deposition and nucleosome assembly

“…Thus, the ordered disassembly and reassembly of nucleosomes is an important paradigm in gene regulation. Chromatin remodeling depends on the recruitment of acetyltransferases that acetylate the four core histones, on the activity of chromatin‐remodeling complexes and on the capacity of histone chaperones to act as a histone acceptors, facilitating their removal from DNA to stimulate transcription (Ito et al , 2000; Asahara et al , 2002; Lorch et al , 2006; Adkins et al , 2007; Sharma & Nyborg, 2008). …”

Activator-dependent p300 Acetylation of Chromatin in Vitro

“…DNA was assembled into nucleosomal arrays by mixing histone octamers and promoter DNA together at a molar ratio of ϳ2.5 in a reaction containing 2 M NaCl in TE (10 mM Tris⅐HCl (pH 7.9) and 0.25 mM EDTA) followed by stepwise dilution of NaCl as described (28), except the chromatin was bound to streptavidin-coated magnetic beads in 0.3 M NaCl in TE after assembly.…”

“…Recombinant Ser133-phosphorylated CREB 327 (pCREB) (27,28) and Tax-His 6 (29) were purified as described (30). Nuclear extract from CEM cells was prepared as described (31).…”