Enzyme kinetics and inhibition of histone acetyltransferase KAT8

• DOI: 10.1016/j.ejmech.2015.10.016
• Publication Date: 2015-10-25T06:28:17Z
• Authors: Hannah Wapenaar; Petra E. van der ...; Matthew R. Groves; Dante Rotili; Antonello Mai; Frank J. Dekker
• Keywords: Models, Molecular; biocatalysis; enzyme inhibitors; molecular structure; dose-response relationship; catalytic mechanism; enzyme kinetics; epigenetics; histone acetylation; KAT8; acetyl coenzyme A; anacardic acids; biocatalysis; dose-response relationship, drug; enzyme inhibitors; histone acetyltransferases; histones; humans; kinetics; models, molecular; molecular structure; structure-activity relationship; Histones; Structure-Activity Relationship; 03 medical and health sciences; models in science; Acetyl Coenzyme A; histones; Drug Discovery; Humans; molecular; Enzyme Inhibitors; humans; anacardic acids; Histone Acetyltransferases; Pharmacology; 0303 health sciences; Dose-Response Relationship, Drug; Molecular Structure; structure-activity relationship; histone acetyltransferases; Enzyme kinetics; Organic Chemistry; Catalytic mechanism; Anacardic Acids; 3. Good health; Kinetics; antagonists & inhibitors; Histone acetylation; kinetics; drug effects; KAT8; Biocatalysis; Epigenetics; catalytic mechanism; enzyme kinetics; epigenetics; histone acetylation; KAT8; acetyl coenzyme A; anacardic acids; biocatalysis; dose-response relationship; drug; enzyme inhibitors; histone acetyltransferases; histones; humans; kinetics; models; molecular; molecular structure; structure-activity relationship; metabolism; acetyl coenzyme A; chemical synthesis

Lysine acetyltransferase 8 (KAT8) is a histone acetyltransferase (HAT) responsible for acetylating lysine 16 on histone H4 (H4K16) and plays a role in cell cycle progression as well as acetylation of the tumor suppressor protein p53. Further studies on its biological function and drug discovery initiatives will benefit from the development of small molecule inhibitors for this enzyme. As a first step towards this aim we investigated the enzyme kinetics of this bi-substrate enzyme. The kinetic experiments indicate a ping-pong mechanism in which the enzyme binds Ac-CoA first, followed by binding of the histone substrate. This mechanism is supported by affinity measurements of both substrates using isothermal titration calorimetry (ITC). Using this information, the KAT8 inhibition of a focused compound collection around the non-selective HAT inhibitor anacardic acid has been investigated. Kinetic studies with anacardic acid were performed, based on which a model for the catalytic activity of KAT8 and the inhibitory action of anacardic acid (AA) was proposed. This enabled the calculation of the inhibition constant Ki of anacardic acid derivatives using an adaptation of the Cheng-Prusoff equation. The results described in this study give insight into the catalytic mechanism of KAT8 and present the first well-characterized small-molecule inhibitors for this HAT.