title: Structures of the apo- and the metal ion-activated forms of the diphtheria tox repressor from Corynebacterium diphtheriae.
abstract: The diphtheria tox repressor (DtxR) of Corynebacterium diphtheriae plays a critical role in the regulation of diphtheria toxin expression and the control of other iron-sensitive genes. The crystal structures of apo-DtxR and of the metal ion-activated form of the repressor have been solved and used to identify motifs involved in DNA and metal ion binding. Residues involved in binding of the activated repressor to the diphtheria tox operator, glutamine 43, arginine 47, and arginine 50, were located and confirmed by site-directed mutagenesis. Previous biochemical and genetic data can be explained in terms of these structures. Conformational differences between apo- and Ni-DtxR are discussed with regard to the mechanism of action of this repressor.
authors.affiliation: Department of Chemistry, Brandeis University, Waltham, MA 02154, USA.
authors.forename: N
authors.initials: N
authors.lastname: Schiering
authors.forename: X
authors.initials: X
authors.lastname: Tao
authors.forename: H
authors.initials: H
authors.lastname: Zeng
authors.forename: J R
authors.initials: JR
authors.lastname: Murphy
authors.forename: G A
authors.initials: GA
authors.lastname: Petsko
authors.forename: D
authors.initials: D
authors.lastname: Ringe
mesh_terms: D000595:Amino Acid Sequence; D001059:Apoproteins / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D003353:Corynebacterium diphtheriae / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D019077:Helix-Turn-Helix Motifs; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009532:Nickel / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C075586:DtxR protein, Corynebacterium diphtheriae; D012097:Repressor Proteins; D009532:Nickel