Activation Domain-Specific and General Transcription Stimulation by Native Histone Acetyltransferase Complexes

Abstract

Recent progress in identifying the catalytic subunits of histone acetyltransferase (HAT) complexes has implicated histone acetylation in the regulation of transcription. Here, we have analyzed the function of two native yeast HAT complexes, SAGA (Spt-Ada-Gcn5 Acetyltransferase) and NuA4 (nucleosome acetyltransferase of H4), in activating transcription from preassembled nucleosomal array templates in vitro. Each complex was tested for the ability to enhance transcription driven by GAL4 derivatives containing either acidic, glutamine-rich, or proline-rich activation domains. On nucleosomal array templates, the SAGA complex selectively stimulates transcription driven by the VP16 acidic activation domain in an acetyl coenzyme A-dependent manner. In contrast, the NuA4 complex facilitates transcription mediated by any of the activation domains tested if allowed to preacetylate the nucleosomal template, indicating a general stimulatory effect of histone H4 acetylation. However, when the extent of acetylation by NuA4 is limited, the complex also preferentially stimulates VP16-driven transcription. SAGA and NuA4 interact directly with the VP16 activation domain but not with a glutamine-rich or proline-rich activation domain. These data suggest that recruitment of the SAGA and NuA4 HAT complexes by the VP16 activation domain contributes to HAT-dependent activation. In addition, extensive H4/H2B acetylation by NuA4 leads to a general activation of transcription, which is independent of activator-NuA4 interactions.

ACKNOWLEDGMENTS

We are grateful to Jacques Côté, Rhea T. Utley, Thomas Owen-Hughes, Ahmed Hanssan, and Michael Meisterernst for providing materials. We thank Sam John, Patrick A. Grant, Thomas Owen-Hughes, Rhea T. Utley, and Jacques Côté for many helpful discussions and critical reading of the manuscript. We also thank Kiyoshi Kawakami and Marissa Vignali for encouragement of this work.

This work was supported by a grant from National Institute of General Medical Sciences. D.J.S. was supported by a postdoctoral fellowship from the Cancer Research Institute. A.E. is a recipient of a postdoctoral fellowship from the Austrian Science Foundation. J.L.W. is an HHMI Associate Investigator.