1ygh
From Proteopedia
HAT DOMAIN OF GCN5 FROM SACCHAROMYCES CEREVISIAE
Structural highlights
FunctionGCN5_YEAST Acetylates histone H2B to form H2BK11ac and H2BK16ac, histone H3 to form H3K9ac, H3K14ac, H3K18ac, H3K23ac, H3K27ac and H3K36ac, with a lower preference histone H4 to form H4K8ac and H4K16ac, and contributes to H2A.Z acetylation. Acetylation of histones gives a specific tag for epigenetic transcription activation. Operates in concert with certain DNA-binding transcriptional activators such as GCN4 or HAP2/3/4. Its acetyltransferase activity seems to be dependent on the association in different multisubunit complexes. Functions as histone acetyltransferase component of the transcription regulatory histone acetylation (HAT) complexes SAGA, SALSA and ADA. SAGA is involved in RNA polymerase II-dependent transcriptional regulation of approximately 10% of yeast genes. At the promoters, SAGA is required for recruitment of the basal transcription machinery. It influences RNA polymerase II transcriptional activity through different activities such as TBP interaction (SPT3, SPT8 and SPT20) and promoter selectivity, interaction with transcription activators (GCN5, ADA2, ADA3 and TRA1), and chromatin modification through histone acetylation (GCN5) and deubiquitination (UBP8). SAGA acetylates nucleosomal histone H3 to some extent (to form H3K9ac, H3K14ac, H3K18ac and H3K23ac). SAGA interacts with DNA via upstream activating sequences (UASs). SALSA, an altered form of SAGA, may be involved in positive transcriptional regulation. The ADA histone acetyltransferase complex preferentially acetylates nucleosomal histones H3 (to form H3K14ac and H3K18ac) and H2B, leading to transcription regulation. SLIK is proposed to have partly overlapping functions with SAGA. It preferentially acetylates methylated histone H3, at least after activation at the GAL1-10 locus.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe yeast GCN5 (yGCN5) transcriptional coactivator 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. Crystal structure and mechanism of histone acetylation of the yeast GCN5 transcriptional coactivator.,Trievel RC, Rojas JR, Sterner DE, Venkataramani RN, Wang L, Zhou J, Allis CD, Berger SL, Marmorstein R Proc Natl Acad Sci U S A. 1999 Aug 3;96(16):8931-6. PMID:10430873[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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