title: The yeast elongator histone acetylase requires Sit4-dependent dephosphorylation for toxin-target capacity.
abstract: Kluyveromyces lactis zymocin, a heterotrimeric toxin complex, imposes a G1 cell cycle block on Saccharomyces cerevisiae that requires the toxin-target (TOT) function of holo-Elongator, a six-subunit histone acetylase. Here, we demonstrate that Elongator is a phospho-complex. Phosphorylation of its largest subunit Tot1 (Elp1) is supported by Kti11, an Elongator-interactor essential for zymocin action. Tot1 dephosphorylation depends on the Sit4 phosphatase and its associators Sap185 and Sap190. Zymocin-resistant cells lacking or overproducing Elongator-associator Tot4 (Kti12), respectively, abolish or intensify Tot1 phosphorylation. Excess Sit4.Sap190 antagonizes the latter scenario to reinstate zymocin sensitivity in multicopy TOT4 cells, suggesting physical competition between Sit4 and Tot4. Consistently, Sit4 and Tot4 mutually oppose Tot1 de-/phosphorylation, which is dispensable for integrity of holo-Elongator but crucial for the TOT-dependent G1 block by zymocin. Moreover, Sit4, Tot4, and Tot1 cofractionate, Sit4 is nucleocytoplasmically localized, and sit4Delta-nuclei retain Tot4. Together with the findings that sit4Delta and totDelta cells phenocopy protection against zymocin and the ceramide-induced G1 block, Sit4 is functionally linked to Elongator in cell cycle events targetable by antizymotics.
authors.affiliation: Biologicum, Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, D-06120 Halle, Saale, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jablonowski
authors.forename: Lars
authors.initials: L
authors.lastname: Fichtner
authors.forename: Michael J R
authors.initials: MJ
authors.lastname: Stark
authors.forename: Raffael
authors.initials: R
authors.lastname: Schaffrath
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D051548:Histone Acetyltransferases; D055646:Killer Factors, Yeast; D009183:Mycotoxins / Q000633:toxicity*; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D054648:Protein Phosphatase 2; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: C459979:KTI11 protein, S cerevisiae; D055646:Killer Factors, Yeast; D009183:Mycotoxins; D010445:Peptide Elongation Factors; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C058975:zymocin; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; C479559:IKI3 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; C104343:SIT4 protein, S cerevisiae