Holo-DtxR

Pohl E, Holmes RK, Hoi WGJ. 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. 1998 273 22420-22427. 

The crystal structures of DtxR and IdeR provide a detailed picture of this protein family (Figure 3.7, Plate 5). The N-terminal domain (residues 1-73) containing a helix-turn-helix motif binds a recognition nucleotide sequence of about 21 base pairs, as is nicely shown in a cocrystal of DNA and DtxR (Pohl et al., 1999). The central domain (74-140) has a function in dimerization the role of the third carboxy-terminal domain (141-230) is uncertain. Although metal-binding sites have been defined in these crystal structures, the mechanism by which metal binding causes the structural changes between apo- and holo-repressor is not clear. 

The crystal structure of metal-ion activated DtxR suggests two, mutually nonexclusive, models for the mechanism of activation of this repressor. Comparison of the apo- and holo-repressors shows a conformational change between the two sub-... 

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