Structural basis for acyl-group discrimination by human Gcn5L2

Acta Crystallogr D Struct Biol. 2016 Jul;72(Pt 7):841-8. doi: 10.1107/S2059798316007907. Epub 2016 Jun 23.


Gcn5 is a conserved acetyltransferase that regulates transcription by acetylating the N-terminal tails of histones. Motivated by recent studies identifying a chemically diverse array of lysine acyl modifications in vivo, the acyl-chain specificity of the acetyltransferase human Gcn5 (Gcn5L2) was examined. Whereas Gcn5L2 robustly catalyzes lysine acetylation, the acyltransferase activity of Gcn5L2 becomes progressively weaker with increasing acyl-chain length. To understand how Gcn5 discriminates between different acyl-CoA molecules, structures of the catalytic domain of human Gcn5L2 bound to propionyl-CoA and butyryl-CoA were determined. Although the active site of Gcn5L2 can accommodate propionyl-CoA and butyryl-CoA without major structural rearrangements, butyryl-CoA adopts a conformation incompatible with catalysis that obstructs the path of the incoming lysine residue and acts as a competitive inhibitor of Gcn5L2 versus acetyl-CoA. These structures demonstrate how Gcn5L2 discriminates between acyl-chain donors and explain why Gcn5L2 has weak activity for acyl moieties that are larger than an acetyl group.

Keywords: Gcn5; acyltransferase; butyryl-CoA; histone acetyltransferase; propionyl-CoA.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylation
  • Acyl Coenzyme A / metabolism
  • Crystallography, X-Ray
  • Humans
  • Models, Molecular
  • Protein Conformation
  • Substrate Specificity
  • p300-CBP Transcription Factors / chemistry*
  • p300-CBP Transcription Factors / metabolism*


  • Acyl Coenzyme A
  • butyryl-coenzyme A
  • propionyl-coenzyme A
  • p300-CBP Transcription Factors
  • p300-CBP-associated factor