Fig. 1
S. acidocaldarius harbors a TetR-family regulator structurally similar to bacterial TetR-like FadR proteins. a Genomic organization of the Saci_1103-Saci_1126 gene cluster. Gene numbers are indicated by displaying the last two digits below each gene arrow. Transcriptional start sites are shown with small arrows, and are based on ref. 37. b Structure of the FadRSa dimer with indication of the different helices (chain A: α1′–α9′; chain B: α1–α9). The acyl-CoA molecule present in chain B is shown as a stick model. c Superposition of the FadRSa and FadRBs (PDB 3WHB) structures. d Structure-based sequence alignment of TetR-family FadR proteins. The alignment is based on a three-dimensional comparison between FadRSa from S. acidocaldarius (PDB 5MWR), FadRBs from B. subtilis (PDB 3WHB)25, FadRBh from B. halodurans (PDB 5GP9)26, and FadR from T. thermophilus (PDB 3ANG)24. Regions harboring structural and sequence similarity are boxed, with identical amino-acid residues indicated as bold white letters on a red background and functionally equivalent residues indicated in red letters. Secondary structure elements and numbering for FadRSa are indicated above the sequences. DNA-binding residues targeted for mutagenesis are indicated with purple triangles, ligand-binding residues with green triangles. FadRBh residues important for DNA binding and ligand binding26 are indicated below the sequences with purple and green asterisks, respectively
