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1: Proc Natl Acad Sci U S A. 2008 Jun 10;105(23):7959-63. Epub 2008 Jun 3.
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The coactivators CBP/p300 and the histone chaperone NAP1 promote transcription-independent nucleosome eviction at the HTLV-1 promoter.

Sharma N, Nyborg JK.

Department of Biochemistry and Molecular Biology, Campus Box 1870, Colorado State University, Fort Collins, CO 80523, USA.

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.

Publication Types:
PMID: 18523016 [PubMed - indexed for MEDLINE]

PMCID: PMC2430344 [Available on 12/10/08]