FIGURE 6.

Sequence alignment. The amino acid sequences of HCAR homologues from 10 species are aligned. The ligating cysteines of the distal and proximal [4Fe-4S] clusters are labeled by empty and solid circles, respectively. The FAD-binding residues whose backbone atoms are involved in FAD interaction are indicated by empty triangles, and those whose side chain atoms are involved are indicated by solid triangles. Residues forming the substrate pocket are indicated by solid squares. His⁴¹⁷ and Asp²³⁷ are labeled with stars.