Iron-Sulfur World in Aerobic and Hyperthermoacidophilic Archaea Sulfolobus

Figure 3

Multiple sequence alignment of the metal-binding sites of selected Rieske-type proteins and rubredoxins (Rd). The cluster-binding motif of S. solfataricus ARF is characteristic of Rieske-type ferredoxins involved in bacterial multicomponent oxygenases, containing two histidyl (blue) and two cysteinyl (green) ligands, and lacks two conserved cysteine residues (black) that serve as the disulfide linkage in high potential, respiratory Rieske proteins [138, 153]. DDBJ-EMBL-GenBank accession codes: bovine mitochondrial cytochrome bc₁-associated Rieske protein fragment, P13272; S. solfataricus ARF (hypothetical ORF c06009), CAA669492, AB047031; P. furiosus rubredoxin, P24297; C. pasteurianum rubredoxin, P00268. The metal-binding motifs are underlined (left), and the structure of the cluster ligand residues of a bovine mitochondrial Rieske protein domain fragment (PDB code, 1rie.pdb) [145] is shown, but with the S. solfataricus ARF numbering (right). Brown square symbols (left), wild-type or mutant proteins containing a [2Fe-2S] cluster; magenta open circles (left), wild-type or mutant proteins containing a Rd-like, mononuclear (Fe/Zn) center.