Crystal structure and mechanism of histone acetylation of the yeast GCN5 transcriptional coactivator

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 16; pp. 8931 - 8936
• Main Authors: Trievel, R.C, Rojas, J.R, Sterner, D.E, Venkataramani, R.N, Wang, L, Zhou, J, Allis, C.D, Berger, S.L, Marmorstein, R
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 03-08-1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Acetylation; Acetyltransferases - chemistry; Acetyltransferases - metabolism; acyltransferases; Amino Acid Sequence; Amino Acid Substitution; binding; Biochemistry; Biological Sciences; Catalysis; coenzyme A; Computer Graphics; Crystallography; Crystallography, X-Ray; crystals; DNA-Binding Proteins; Enzymes; Fungal Proteins - chemistry; Fungal Proteins - metabolism; histone acetyltransferase; Histone Acetyltransferases; Histones; Histones - metabolism; Humans; Models, Molecular; molecular conformation; Molecular Sequence Data; Molecules; Mutagenesis, Site-Directed; mutants; pdb/1ygh; Plasmids; Protein Conformation; Protein Kinases - chemistry; Protein Kinases - metabolism; Proteins; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins; Sequence Alignment; Sequence homology; Sequence Homology, Amino Acid; Serratia marcescens; Trans-Activators - chemistry; Trans-Activators - metabolism; transcription factors; Transcriptional activation; X-ray diffraction; Yeast; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.16.8931

The yeast GCN5 (yGCN5) transcriptional co-activator functions as a histone acetyltransferase (HAT) to promote transcriptional activation. Here, we present the high resolution crystal structure of the HAT domain of yGCN5 and probe the functional importance of a conserved glutamate residue. The structure reveals a central protein core associated with AcCoA binding that appears to be structurally conserved among a superfamily of N-acetyltransferases, including yeast histone acetyltransferase 1 and Serratia marcescens aminoglycoside 3-N-acetyltransferase. A pronounced cleft lying above this core, and flanked by N- and C-terminal regions that show no sequence conservation within N-acetyltransferase enzymes, is implicated by cross-species conservation and mutagenesis studies to be a site for histone substrate binding and catalysis. Located at the bottom of this cleft is a conserved glutamate residue (E173) that is in position to play an important catalytic role in histone acetylation. Functional analysis of an E173Q mutant yGCN5 protein implicates glutamate 173 to function as a general base for catalysis. Together, a correlation of the yGCN5 structure with functionally debilitating yGCN5 mutations provides a paradigm for understanding the structure/function relationships of the growing number of transcriptional regulators that function as histone acetyltransferase enzymes.