FIG. 4.

Multiple sequence analysis of SoxA proteins. The amino acid sequences of the amino terminus of the mature R. sulfidophilum SoxA protein and of internal SoxA peptides determined by protein sequencing in this work are shown on the line marked “Peptides.” Experimentally determined (R. sulfidophilum and P. pantotrophus) or predicted signal peptides are underlined. No signal peptide is shown for the A. aeolicus protein due to uncertainty in the identity of the precursor start codon. The consensus c-type cytochrome Cys-Xaa-Xaa-Cys-His heme attachment sites and conserved cysteines that are the proposed heme iron ligands in R. sulfidophilum SoxA are boxed. The sources of the sequence data are the same as in Fig. 3 with the addition of C. limicola cytochrome c₅₅₁ from reference 23 and Thiobacillus sp. strain KCT001 SoxA from reference 35. The numbering on the individual sequences refers to the mature protein.