1DDN

DIPHTHERIA TOX REPRESSOR (C102D MUTANT)/TOX DNA OPERATOR COMPLEX

Summary for 1DDN

• Entry DOI: 10.2210/pdb1ddn/pdb
• Descriptor: 33 BASE DNA CONTAINING TOXIN OPERATOR, DIPHTHERIA TOX REPRESSOR, NICKEL (II) ION, ... (5 entities in total)
• Functional Keywords: complex (regulatory protein-dna), diphtheria tox repressor, transcription regulation, dna-binding regulatory protein, iron-regulated repressor, dna- protein, dna-repressor complex, gene regulation-dna complex, gene regulation/dna
• Biological source: Corynebacterium diphtheriae
• Total number of polymer chains: 6
• Total formula weight: 122206.70

Authors

White, A.,Ding, X.,Vanderspek, J.C.,Murphy, J.R.,Ringe, D. (deposition date: 1998-06-23, release date: 1998-10-14, Last modification date: 2023-08-02)

Primary citation

White, A.,Ding, X.,vanderSpek, J.C.,Murphy, J.R.,Ringe, D.
Structure of the metal-ion-activated diphtheria toxin repressor/tox operator complex.
Nature, 394:502-506, 1998

PubMed Abstract: The virulent phenotype of the pathogenic bacterium Corynebacterium diphtheriae is conferred by diphtheria toxin, whose expression is an adaptive response to low concentrations of iron. The expression of the toxin gene (tox) is regulated by the repressor DtxR, which is activated by transition metal ions. X-ray crystal structures of DtxR with and without (apo-form) its coordinated transition metal ion have established the general architecture of the repressor, identified the location of the metal-binding sites, and revealed a metal-ion-triggered subunit-subunit 'caliper-like' conformational change. Here we report the three-dimensional crystal structure of the complex between a biologically active Ni(II)-bound DtxR(C102D) mutant, in which a cysteine is replaced by an aspartate at residue 102, and a 33-base-pair DNA segment containing the toxin operator toxO. This structure shows that DNA interacts with two dimeric repressor proteins bound to opposite sides of the tox operator. We propose that a metal-ion-induced helix-to-coil structural transition in the amino-terminal region of the protein is partly responsible for the unique mode of repressor activation by transition metal ions.

PubMed: 9697776
DOI: 10.1038/28893

Experimental method

X-RAY DIFFRACTION (3 Å)