title: Subunits of ADA-two-A-containing (ATAC) or Spt-Ada-Gcn5-acetyltrasferase (SAGA) Coactivator Complexes Enhance the Acetyltransferase Activity of GCN5.
abstract: Histone acetyl transferases (HATs) play a crucial role in eukaryotes by regulating chromatin architecture and locus specific transcription. GCN5 (KAT2A) is a member of the GNAT (Gcn5-related N-acetyltransferase) family of HATs. In metazoans this enzyme is found in two functionally distinct coactivator complexes, SAGA (Spt Ada Gcn5 acetyltransferase) and ATAC (Ada Two A-containing). These two multiprotein complexes comprise complex-specific and shared subunits, which are organized in functional modules. The HAT module of ATAC is composed of GCN5, ADA2a, ADA3, and SGF29, whereas in the SAGA HAT module ADA2b is present instead of ADA2a. To better understand how the activity of human (h) hGCN5 is regulated in the two related, but different, HAT complexes we carried out in vitro HAT assays. We compared the activity of hGCN5 alone with its activity when it was part of purified recombinant hATAC or hSAGA HAT modules or endogenous hATAC or hSAGA complexes using histone tail peptides and full-length histones as substrates. We demonstrated that the subunit environment of the HAT complexes into which GCN5 incorporates determines the enhancement of GCN5 activity. On histone peptides we show that all the tested GCN5-containing complexes acetylate mainly histone H3K14. Our results suggest a stronger influence of ADA2b as compared with ADA2a on the activity of GCN5. However, the lysine acetylation specificity of GCN5 on histone tails or full-length histones was not changed when incorporated in the HAT modules of ATAC or SAGA complexes. Our results thus demonstrate that the catalytic activity of GCN5 is stimulated by subunits of the ADA2a- or ADA2b-containing HAT modules and is further increased by incorporation of the distinct HAT modules in the ATAC or SAGA holo-complexes.
authors.affiliation: From the Cellular Signaling and Nuclear Dynamics Program and.
authors.forename: Anne
authors.initials: A
authors.lastname: Riss
authors.affiliation: From the Cellular Signaling and Nuclear Dynamics Program and.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Scheer
authors.affiliation: Proteomics platform, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR 7104, INSERM U964, Université de Strasbourg, BP 10142, 67404 Illkirch Cedex, CU de Strasbourg, France and.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Joint
authors.affiliation: EMBL Grenoble Outstation, 6 rue Jules Horowitz BP 181, F-38042 Grenoble Cedex, France and The School of Biochemistry, University of Bristol, University Walk, Clifton BS8 1TD, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Trowitzsch
authors.affiliation: EMBL Grenoble Outstation, 6 rue Jules Horowitz BP 181, F-38042 Grenoble Cedex, France and The School of Biochemistry, University of Bristol, University Walk, Clifton BS8 1TD, United Kingdom.
authors.forename: Imre
authors.initials: I
authors.lastname: Berger
authors.affiliation: From the Cellular Signaling and Nuclear Dynamics Program and laszlo@igbmc.fr.
authors.forename: László
authors.initials: L
authors.lastname: Tora
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D004268:DNA-Binding Proteins; D051548:Histone Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D061987:Sf9 Cells; D018411:Spodoptera; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000099224:p300-CBP-Associated Factor
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D051548:Histone Acetyltransferases; D046912:Multiprotein Complexes; D014157:Transcription Factors; C097695:TADA2A protein, human; C444103:TADA3 protein, human; C501179:KAT2A protein, human; D000099224:p300-CBP-Associated Factor
keywords: KAT2A; chromatin; chromatin modification; chromatin regulation; complex; histone; histone acetylase; histone acetylation; human; mass spectrometry (MS)