FIG. 4.

Schematic illustration of the relative contributions of DmpR (open boxes) and XylR (shaded boxes) amino acid sequences to the A-domains of the derivatives tested for aromatic responsiveness (Fig. 3). The derivatives are classified into four response profile groups as described in the text. The arrowheads mark the locations of single-amino-acid substitutions that give rise to novel effector response abilities of DmpR (open arrowheads) and XylR (shaded arrowheads) as described in the text. wt, wild type. Narrow ends indicate the extent of β-domain linker sequences (Fig. 1), while stippled boxes indicate the junction points defined in Table 1.