title: Chaperone-mediated acetylation of histones by Rtt109 identified by quantitative proteomics.
abstract: Rtt109 is a fungal-specific histone acetyltransferase (HAT) that associates with either Vps75 or Asf1 to acetylate histone H3. Recent biochemical and structural studies suggest that site-specific acetylation of H3 by Rtt109 is dictated by the binding chaperone where Rtt109-Asf1 acetylates K56, while Rtt109-Vps75 acetylates K9 and K27. To gain further insights into the roles of Vps75 and Asf1 in directing site-specific acetylation of H3, we used quantitative proteomics to profile the global and site-specific changes in H3 and H4 during in vitro acetylation assays with Rtt109 and its chaperones. Our analyses showed that Rtt109-Vps75 preferentially acetylates H3 K9 and K23, the former residue being the major acetylation site. At high enzyme-to-substrate ratio, Rtt109 also acetylated K14, K18, K27 and to a lower extent K56 of histone H3. Importantly, this study revealed that in contrast to Rtt109-Vps75, Rtt109-Asf1 displayed a far greater site-specificity, with K56 being the primary site of acetylation. For the first time, we also report the acetylation of histone H4 K12 by Rtt109-Vps75, whereas Rtt109-Asf1 showed no detectable activity toward H4. This article is part of a Special Issue entitled: From protein structures to clinical applications.
authors.affiliation: Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada.
authors.forename: Nebiyu
authors.initials: N
authors.lastname: Abshiru
authors.forename: Kevin
authors.initials: K
authors.lastname: Ippersiel
authors.forename: Yong
authors.initials: Y
authors.lastname: Tang
authors.forename: Hua
authors.initials: H
authors.lastname: Yuan
authors.forename: Ronen
authors.initials: R
authors.lastname: Marmorstein
authors.forename: Alain
authors.initials: A
authors.lastname: Verreault
authors.forename: Pierre
authors.initials: P
authors.lastname: Thibault
mesh_terms: D000107:Acetylation; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D051548:Histone Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C109731:ASF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D006657:Histones; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; C525548:Vps75 protein, S cerevisiae; D051548:Histone Acetyltransferases; C517120:Rtt109 protein, S cerevisiae