title: Cysteine Mutational Studies Provide Insight into a Thiol-Based Redox Switch Mechanism of Metal and DNA Binding in FurA from Anabaena sp. PCC 7120.
abstract: The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron homeostasis in most prokaryotes. FurA from Anabaena sp. PCC 7120 contains five cysteine residues, four of them arranged in two redox-active CXXC motifs. The protein needs not only metal but also reducing conditions to remain fully active in vitro. Through a mutational study of the cysteine residues present in FurA, we have investigated their involvement in metal and DNA binding.
  
  
  
  Residue C101that belongs to a conserved CXXC motif plays an essential role in both metal and DNA binding activities in vitro. Substitution of C101by serine impairs DNA and metal binding abilities of FurA. Isothermal titration calorimetry measurements show that the redox state of C101is responsible for the protein ability to coordinate the metal corepressor. Moreover, the redox state of C101varies with the presence or absence of C104or C133, suggesting that the environments of these cysteines are mutually interdependent.
  
  
  
  We propose that C101is part of a thiol/disulfide redox switch that determines FurA ability to bind the metal corepressor.
  
  
  
  This mechanism supports a novel feature of a Fur protein that emerges as a regulator, which connects the response to changes in the intracellular redox state and iron management in cyanobacteria. Antioxid. Redox Signal. 00, 000-000.
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .
authors.forename: Laura
authors.initials: L
authors.lastname: Botello-Morte
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .
authors.forename: Silvia
authors.initials: S
authors.lastname: Pellicer
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .
authors.forename: Violeta C
authors.initials: VC
authors.lastname: Sein-Echaluce
authors.affiliation: 3 Institut of Molecular and Cellular Biology, Miguel Hernández University of Elche , Elche, Spain .
authors.forename: Lellys M
authors.initials: LM
authors.lastname: Contreras
authors.affiliation: 2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .|3 Institut of Molecular and Cellular Biology, Miguel Hernández University of Elche , Elche, Spain .
authors.forename: José Luis
authors.initials: JL
authors.lastname: Neira
authors.affiliation: 2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .|4 IIS Aragon-Aragon Health Science Institute (IACS) and Networked Biomedical Research Center of Hepatic and Digestive Diseases (CIBERehd) , Zaragoza, Spain .
authors.forename: Olga
authors.initials: O
authors.lastname: Abián
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .|5 ARAID Foundation , Government of Aragón, Zaragoza, Spain .
authors.forename: Adrián
authors.initials: A
authors.lastname: Velázquez-Campoy
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Peleato
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .
authors.forename: María F
authors.initials: MF
authors.lastname: Fillat
authors.affiliation: 1 Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza , Zaragoza, Spain .|2 Institute for Biocomputation and Physics of Complex Systems (BIFI)-Associated Unit to IQRS-CSIC, University of Zaragoza , Zaragoza, Spain .
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Bes