Structure of Tetrahymena GCN5 bound to coenzyme A and a histone H3 peptide.Rojas, J.R., Trievel, R.C., Zhou, J., Mo, Y., Li, X., Berger, S.L., Allis, C.D., Marmorstein, R.
(1999) Nature 401: 93-98
- PubMed: 10485713
- DOI: 10.1038/43487
- Primary Citation of Related Structures:  1QSR, 1QST
- PubMed 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 betwe ...
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.
The Wistar Institute, Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA.