Dual roles of p300 in chromatin assembly and transcriptional activation in cooperation with nucleosome assembly protein 1 in vitro.

In a yeast two-hybrid screen to identify proteins that bind to the KIX domain of the coactivator p300, we obtained cDNAs encoding nucleosome assembly protein 1 (NAP-1), a 60-kDa histone H2A-H2B shuttling protein that promotes histone deposition. p300 associates preferentially with the H2A-H2B-bound form of NAP-1 rather than with the ...
unbound form of NAP-1. Formation of NAP-1-p300 complexes was found to increase during S phase, suggesting a potential role for p300 in chromatin assembly. In micrococcal nuclease and supercoiling assays, addition of p300 promoted efficient chromatin assembly in vitro in conjunction with NAP-1 and ATP-utilizing chromatin assembly and remodeling factor; this effect was dependent in part on the intrinsic histone acetyltransferase activity of p300. Surprisingly, NAP-1 potently inhibited acetylation of core histones by p300, suggesting that efficient assembly requires acetylation of either NAP-1 or p300 itself. As p300 acted cooperatively with NAP-1 in stimulating transcription from a chromatin template in vitro, our results suggest a dual role of NAP-1-p300 complexes in promoting chromatin assembly and transcriptional activation.
Mesh Terms:
Animals, Blotting, Western, Cell Cycle Proteins, Cell Nucleus, Chromatin, DNA, Drosophila, Drosophila Proteins, Electrophoresis, Polyacrylamide Gel, HeLa Cells, Humans, Nuclear Proteins, Nucleosome Assembly Protein 1, Nucleosomes, Protein Binding, Proteins, Recombinant Proteins, Trans-Activators, Transcription, Genetic, Transcriptional Activation, Two-Hybrid System Techniques, Yeasts
Mol. Cell. Biol.
Date: May. 01, 2002
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