FIG. 2.

Alignment of members of the FNR family. An alignment created by the Genetics Computer Group program Pileup is shown. The sequences used were DnrE and DnrD from Pseudomonas stutzeri, NNR from P. denitrificans, NarR from P. pantotrophus, and FNR from E. coli. Residues conserved among at least four of the five aligned sequences are shown in bold. The predicted helix-turn-helix DNA binding domain is marked. The cysteine residues that are responsible for binding the oxygen-responsive iron-sulfur cluster in FNR are marked with asterisks. Glycine residue 85 (FNR numbering), which is involved in making contact with RNA polymerase (in all of the FNR homologues except NarR), is marked with a cross.