Base-pair structure, recognition

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. 

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