FIG. 1.

Conserved residues in NorR-NTD and amino acid exchanges. Boxed residues are strictly conserved in NorR orthologs; encircled residues are conserved in the majority of orthologs. Sequence positions of marked residues are indicated. Examples of alternative residues are given below the sequence along with the corresponding organism: Bxv, Burkholderia xenovorans LB400; Ppr, Photobacterium profundum SS9; Avn, Azotobacter vinelandii AvOP; Prm, Polaromonas sp. strain JS666. A conserved tyrosine that is replaced by phenylalanine in a distinct subset of NorR orthologs (see text for details) is marked by a diamond-shaped outline (middle sequence row). Arrows denote exchanges constructed in this study.