title: Sas4 and Sas5 are required for the histone acetyltransferase activity of Sas2 in the SAS complex.
abstract: The SAS2 gene is involved in transcriptional silencing in Saccharomyces cerevisiae. Based on its primary sequence, the Sas2 protein is predicted to be a member of the MYST family of histone acetyltransferases (HATs). Sas2 forms a complex with Sas4 and Sas5, which are required for its silencing function. Here we show that recombinant Sas2 has HAT activity that absolutely requires Sas4 and is stimulated by Sas5. The recombinant SAS complex acetylates H4 lysine 16 and H3 lysine 14. Furthermore, a purified SAS complex from yeast shows similar activity and specificity. In contrast to other MYST HATs, neither the recombinant nor the native SAS complex acetylated nucleosomal histones under conditions that were optimum for acetylating free histones. Finally, although the SAS subunits interact genetically and physically with Asf1, a histone deposition factor, association of H3 and H4 with Asf1 blocks their acetylation by the SAS complex, raising the possibility that the SAS HAT complex may acetylate free histones prior to their deposition onto DNA by Asf1 or CAF-I.
authors.affiliation: Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Sutton
authors.forename: Wei-Jong
authors.initials: WJ
authors.lastname: Shia
authors.forename: David
authors.initials: D
authors.lastname: Band
authors.forename: Paul D
authors.initials: PD
authors.lastname: Kaufman
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Osada
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Workman
authors.forename: Rolf
authors.initials: R
authors.lastname: Sternglanz
mesh_terms: D000107:Acetylation; D000123:Acetyltransferases / Q000235:genetics* / Q000378:metabolism; D004789:Enzyme Activation; D020868:Gene Silencing; D051548:Histone Acetyltransferases; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000123:Acetyltransferases; C475088:Sas4 protein, S cerevisiae; C475089:Sas5 protein, S cerevisiae; D051548:Histone Acetyltransferases; C469266:Sas2 protein, S cerevisiae