Catalytic component of the NuA4 histone acetyltransferase (HAT), a multiprotein complex involved in epigenetic transcriptional activation of selected genes principally by acetylation of nucleosomal histones H4, H3, H2B, H2A and H2A variant H2A.Z (PubMed:9520405, PubMed:12379856, PubMed:10082517, PubMed:10835360, PubMed:10911987, PubMed:12353039, PubMed:15045029, PubMed:15175650, PubMed:15494307, PubMed:15923609, PubMed:16543223, PubMed:18245364, PubMed:9858608). Acetylates histone H4 to form H4K5ac, H4K8ac, H4K12ac and H4K16ac, histone H3 to form H3K14ac, histone H2B to form H2BK16ac, histone H2A to form H2AK4ac and H2AK7ac, and histone variant H2A.Z to form H2A.ZK14ac (PubMed:10082517, PubMed:10835360, PubMed:10911987, PubMed:12353039, PubMed:15045029, PubMed:15175650, PubMed:15494307, PubMed:15923609, PubMed:18245364, PubMed:9858608). Acetylation of histones gives a specific tag for epigenetic transcription initiation and elongation (PubMed:16543223, PubMed:19822662). Acetylation of histone H4 is essential for DNA double-strand break repair through homologous recombination (PubMed:10082517, PubMed:10835360, PubMed:10911987, PubMed:12353039, PubMed:15045029, PubMed:15175650, PubMed:15494307, PubMed:15923609, PubMed:18245364, PubMed:9858608). Involved in cell cycle progression (PubMed:10082517, PubMed:10835360, PubMed:10911987, PubMed:12353039, PubMed:15045029, PubMed:15175650, PubMed:15494307, PubMed:15923609, PubMed:18245364, PubMed:9858608). Recruitment to promoters depends on H3K4me (PubMed:10082517, PubMed:10835360, PubMed:10911987, PubMed:12353039, PubMed:15045029, PubMed:15175650, PubMed:15494307, PubMed:15923609, PubMed:18245364, PubMed:9858608). Also acetylates non-histone proteins, such as ATG3 and PAH1 (PubMed:22539722, PubMed:29765047). Regulates autophagy by acetylating ATG3, controlling interaction the interaction between ATG3 and ATG8 and ATG8 lipidation (PubMed:22539722). Acts as a regulator of fatty-acid-induced triacylglycerol synthesis by catalyzing acetylation of PAH1, thereby promoting the synthesis of diacylglycerol (PubMed:29765047). In addition to protein acetyltransferase, can use different acyl-CoA substrates, such as 2-hydroxyisobutanoyl-CoA (2-hydroxyisobutyryl-CoA) or (2E)-butenoyl-CoA (crotonyl-CoA), and is able to mediate protein 2-hydroxyisobutyrylation and crotonylation, respectively (PubMed:31699900). Catalyzes histone crotonylation (PubMed:31699900). acetyl-CoA + L-lysyl-[histone] = CoA + H(+) + N(6)-acetyl-L-lysyl-[histone] acetyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-acetyl-L-lysyl-[protein] 2-hydroxyisobutanoyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-(2-hydroxyisobutanoyl)-L-lysyl-[protein] (2E)-butenoyl-CoA + L-lysyl-[protein] = CoA + H(+) + N(6)-(2E)-butenoyl-L-lysyl-[protein] Component of the NuA4 histone acetyltransferase complex composed of at least ACT1, ARP4, EAF3, EAF5, EAF6, EAF7, EPL1, ESA1, SWC4, TRA1, VID21, YAF9 and YNG2. The complex interacts with histones H4 (HHF1 and HHF2), H3 (HHT1 and HHT2) and H2A (HTA1 and HTA2). The ESA1-RPD3 motif is common to ESA1 and RPD3 and is required for ESA1 histone acetyl-transferase (HAT) activity and RPD3 histone deacetylase (HDAC) activity. Autoacetylation at Lys-262 is required for proper function. Present with 1170 molecules/cell in log phase SD medium. Belongs to the MYST (SAS/MOZ) family. The catalytic mechanisms is still under debate. Cys-304 was proposed to function as a nucleophile that forms a covalent intermediate with acetyl-CoA during the reaction (PubMed:12368900), and indeed the residue can be acetylated (in vitro) (PubMed:12368900 and PubMed:17223684). Depending on the assay system, mutation of Cys-304 leads to reduced or undetectable activity, indicating that is plays an important role. Still, mutation of Cys-304 has only a minor effect on the catalytic activity of the NuA4 histone acetyltransferase (HAT) complex (PubMed:17223684), making it unlikely that this residue functions as the catalytic nucleophile.