title: Human histone acetyltransferase GCN5 exists in a stable macromolecular complex lacking the adapter ADA2.
abstract: Acetylation of core histones is an important regulatory step in transcriptional activation from chromatin templates. The yeast transcriptional coactivator protein GCN5 was recently shown to be a nuclear histone acetyltransferase (HAT). Genetic and biochemical studies in yeast suggest that GCN5 functions with the adapter proteins ADA1, ADA2, ADA3, and ADA5 in a heteromeric complex. We have established conditions for chromatographic fractionation of HATs and ADA2 from human K562 erythroleukemia cells. Gel-filtration chromatography revealed two populations of GCN5 with Stokes' radii of 67 and 33 A, consistent with a large macromolecular complex and a monomer, respectively. The GCN5-related HAT, PCAF, was resolved as a stable complex with a Stokes' radius of 74 A. The HAT complexes were resistant to 0.3 M NaCl and DNase I. ADA2 was characterized by a Stokes' radius of 35 A, consistent with a monomer. Thus, in contrast to the stable GCN5-adapter complex in yeast, human GCN5 and ADA2 are not stably associated with each other. The implications of this result are discussed vis-a-vis the mechanism of recruitment of GCN5 to regulatory regions of genes.
authors.affiliation: Department of Pharmacology, University of Wisconsin Medical School, 387 Medical Science Building, 1300 University Avenue, Madison, Wisconsin 53706, USA.
authors.forename: E C
authors.initials: EC
authors.lastname: Forsberg
authors.forename: L T
authors.initials: LT
authors.lastname: Lam
authors.forename: X J
authors.initials: XJ
authors.lastname: Yang
authors.forename: Y
authors.initials: Y
authors.lastname: Nakatani
authors.forename: E H
authors.initials: EH
authors.lastname: Bresnick
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000737:chemistry; D002843:Chromatin / Q000737:chemistry; D002850:Chromatography, Gel; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins; D003850:Deoxyribonuclease I / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D006367:HeLa Cells / Q000737:chemistry; D051548:Histone Acetyltransferases; D006801:Humans; D019901:Locus Control Region / Q000235:genetics; D008958:Models, Molecular; D011487:Protein Conformation; D012045:Regulatory Sequences, Nucleic Acid; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D002843:Chromatin; D004247:DNA; D004268:DNA-Binding Proteins; D003850:Deoxyribonuclease I; D005656:Fungal Proteins; D051548:Histone Acetyltransferases; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C097695:TADA2A protein, human; C501179:KAT2A protein, human