Investigating the GCN5 Histone Acetyltransferase Chemical Mechanism

Abstract

Enzyme catalyzed protein acetylation involves the transfer of an acetyl group to a lysine side chain within the substrate. This process serves many vital cellular purposes including the regulation of gene expression and controlling of the circadian rhythm. Defects in enzymatic acetylation have been linked to many common diseases such as cancer, insomnia, and anemia. Despite decades of research into the biological function of protein acetylation, the enzymatic mechanism of acetyl‐transfer is unknown. We have worked to characterize the mechanism of acetyl‐transfer utilized by the yeast protein acetyltransferase General Control Nonderepressible 5 (GCN5) using deuterium solvent isotope effects, Brønsted‐beta analysis, and competitive inhibition studies. These analyses have allowed us to characterize the occurrence of proton transfer during catalysis as well as gain a general knowledge of the transition state structure. These results will be coupled with QM/MM computational modeling of the GCN5 acetyl‐transfer reaction in order to gain an explicit understanding of the mechanism of catalysis. The collection of these results set the groundwork for further investigation into the catalysis mechanisms of other acetyltransferases and may aid in development of treatment for acetyl‐transfer associated illness.Support or Funding Information‐Jeffress Trust Awards Program in Interdisciplinary Research‐NSF REU: CHE‐1461175