title: Structure of Tetrahymena GCN5 bound to coenzyme A and a histone H3 peptide.
abstract: Gene activation is a highly regulated process that requires the coordinated action of proteins to relieve chromatin repression and to promote transcriptional activation. Nuclear histone acetyltransferase (HAT) enzymes provide a mechanistic link between chromatin destabilization and gene activation by acetylating the epsilon-amino group of specific lysine residues within the aminoterminal tails of core histones to facilitate access to DNA by transcriptional activators. Here we report the high-resolution crystal structure of the HAT domain of Tetrahymena GCN5 (tGCN5) bound with both its physiologically relevant ligands, coenzyme A (CoA) and a histone H3 peptide, and the structures of nascent tGCN5 and a tGCN5/acetyl-CoA complex. Our structural data reveal histone-binding specificity for a random-coil structure containing a G-K-X-P recognition sequence, and show that CoA is essential for reorienting the enzyme for histone binding. Catalysis appears to involve water-mediated proton extraction from the substrate lysine by a glutamic acid general base and a backbone amide that stabilizes the transition-state reaction intermediate. Comparison with related N-acetyltransferases indicates a conserved structural framework for CoA binding and catalysis, and structural variability in regions associated with substrate-specific binding.
authors.affiliation: The Wistar Institute, Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Rojas
authors.forename: R C
authors.initials: RC
authors.lastname: Trievel
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: Y
authors.initials: Y
authors.lastname: Mo
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: S L
authors.initials: SL
authors.lastname: Berger
authors.forename: C D
authors.initials: CD
authors.lastname: Allis
authors.forename: R
authors.initials: R
authors.lastname: Marmorstein
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003065:Coenzyme A / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D051548:Histone Acetyltransferases; D006657:Histones / Q000737:chemistry* / Q000378:metabolism; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D013768:Tetrahymena / Q000201:enzymology*; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D003065:Coenzyme A; D051548:Histone Acetyltransferases; D006657:Histones; D046911:Macromolecular Substances; C120128:tGCN5 histone acetyltransferase; D000099224:p300-CBP-Associated Factor