1XCV

Crystal Structure Of (H79AC102D)Dtxr complexed with Nickel(II)

Summary for 1XCV

• Entry DOI: 10.2210/pdb1xcv/pdb
• Related: 1P92 2TDX
• Descriptor: Diphtheria toxin repressor mutant, NICKEL (II) ION (3 entities in total)
• Functional Keywords: helix-turn-helix, dna binding protein
• Biological source: Corynebacterium diphtheriae
• Cellular location: Cytoplasm: P33120
• Total number of polymer chains: 1
• Total formula weight: 15767.66

Authors

D'aquino, J.A.,Ringe, D. (deposition date: 2004-09-03, release date: 2005-08-16, Last modification date: 2023-08-23)

Primary citation

D'Aquino, J.A.,Tetenbaum-Novatt, J.,White, A.,Berkovitch, F.,Ringe, D.
Mechanism of metal ion activation of the diphtheria toxin repressor DtxR.
Proc.Natl.Acad.Sci.USA, 102:18408-18413, 2005

PubMed Abstract: The diphtheria toxin repressor (DtxR) is a metal ion-activated transcriptional regulator that has been linked to the virulence of Corynebacterium diphtheriae. Structure determination has shown that there are two metal ion binding sites per repressor monomer, and site-directed mutagenesis has demonstrated that binding site 2 (primary) is essential for recognition of the target DNA repressor, leaving the role of binding site 1 (ancillary) unclear. Calorimetric techniques have demonstrated that although binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 x 10(-7), binding site 2 (primary) is a low-affinity binding site with a binding constant of 6.3 x 10(-4). These two binding sites act in an independent fashion, and their contribution can be easily dissected by traditional mutational analysis. Our results clearly demonstrate that binding site 1 (ancillary) is the first one to be occupied during metal ion activation, playing a critical role in stabilization of the repressor. In addition, structural data obtained for the mutants Ni-DtxR(H79A,C102D), reported here, and the previously reported DtxR(H79A) have allowed us to propose a mechanism of metal activation for DtxR.

PubMed: 16352732
DOI: 10.1073/pnas.0500908102

Experimental method

X-RAY DIFFRACTION (2.1 Å)