title: The basic leucine zipper stress response regulator Yap5 senses high-iron conditions by coordination of [2Fe-2S] clusters.
abstract: Iron is an essential, yet at elevated concentrations toxic trace element. To date, the mechanisms of iron sensing by eukaryotic iron-responsive transcription factors are poorly understood. The Saccharomyces cerevisiae transcription factor Yap5, a member of the Yap family of bZIP stress response regulators, administrates the adaptive response to high-iron conditions. Despite the central role of the iron-sensing process for cell viability, the molecule perceived by Yap5 and the underlying regulatory mechanisms are unknown. Here, we show that Yap5 senses high-iron conditions by two Fe/S clusters bound to its activator domain (Yap5-AD). The more stable iron-regulatory Fe/S cluster at the N-terminal cysteine-rich domain (n-CRD) of Yap5 is detected in vivo and in vitro. The second cluster coordinated by the C-terminal CRD can only be shown after chemical reconstitution, since it is bound in a labile fashion. Both clusters are of the [2Fe-2S] type as characterized by UV/visible (UV/Vis), circular dichroism, electron paramagnetic resonance (EPR), and Mössbauer spectroscopy. Fe/S cluster binding to Yap5-AD induces a conformational change that may activate transcription. The cluster-binding motif of the n-CRD domain is highly conserved in HapX-like transcription factors of pathogenic fungi and thus may represent a general sensor module common to many eukaryotic stress response regulators.
authors.affiliation: Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Rietzschel
authors.affiliation: Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany Department of Chemistry, University of Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Pierik
authors.affiliation: Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.affiliation: Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Marburg, Germany lill@staff.uni-marburg.de.
authors.forename: Roland
authors.initials: R
authors.lastname: Lill
authors.affiliation: Institut für Zytobiologie und Zytopathologie, Philipps-Universität, Marburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Mühlenhoff
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D007501:Iron / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D016350:Leucine Zippers / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; C089360:CCC1 protein, S cerevisiae; D027682:Cation Transport Proteins; D007506:Iron-Sulfur Proteins; D029701:Saccharomyces cerevisiae Proteins; C526591:Yap5 protein, S cerevisiae; D013455:Sulfur; D007501:Iron; D003545:Cysteine