1BI1

STRUCTURE OF APO-AND HOLO-DIPHTHERIA TOXIN REPRESSOR

Summary for 1BI1

• Entry DOI: 10.2210/pdb1bi1/pdb
• Descriptor: DIPHTHERIA TOXIN REPRESSOR (2 entities in total)
• Functional Keywords: repressor, transcription regulation, dna-binding, iron
• Biological source: Corynebacterium diphtheriae
• Total number of polymer chains: 1
• Total formula weight: 25381.86

Authors

Pohl, E.,Hol, W.G.J. (deposition date: 1998-06-21, release date: 1999-06-22, Last modification date: 2024-11-13)

Primary citation

Pohl, E.,Holmes, R.K.,Hol, W.G.
Motion of the DNA-binding domain with respect to the core of the diphtheria toxin repressor (DtxR) revealed in the crystal structures of apo- and holo-DtxR.
J.Biol.Chem., 273:22420-22427, 1998

PubMed Abstract: The diphtheria toxin repressor (DtxR) from Corynebacterium diphtheriae is a divalent metal-activated repressor of chromosomal genes that encode proteins responsible for siderophore-mediated iron uptake and also of the gene of certain corynebacteriophages that encodes diphtheria toxin. DtxR consists of two 25.3-kDa three-domain subunits and is a member of a family of related repressor proteins in several Gram-positive bacterial species, some of which are important human pathogens. In this paper, we report on the first high resolution crystal structures of apo-DtxR in two related space groups. In addition, crystal structures of Zn-DtxR were determined in the same two space groups. The resolutions of the structures range from 2.2 to 2.4 A. The four refined models of the apo- and the holo-repressor exhibit quite similar metal binding centers, which do, however, show higher thermal motion in the apo-structures. All four structures reported differ from each other in one important aspect. The N-terminal DNA-binding domain and the last 20 residues of the dimerization domain of each subunit move significantly with respect to the core of the DtxR dimer, which consists of residues 74-120 from both subunits. These results provide the first indication of a conformational change that may occur upon binding of the holo-repressor to DNA.

PubMed: 9712865
DOI: 10.1074/jbc.273.35.22420

Experimental method

X-RAY DIFFRACTION (2.2 Å)