Multiple sequence alignment of SORs between A. thiooxidans and other species. Protein sequences were aligned by the DNAMAN multiple sequence alignment program. The putative domains in SOR were boxed by the rectangle. And the conserved domains V-G-P-K-V-C32, H87-E-E-M-H91 and C102-XX-C105 were indicated by the rectangle A, B, C, respectively. Abbreviations: A. thiooxidans, Acidithiobacillus thiooxidans; A. caldus, Acidithiobacillus caldus (WP_004871908); A. ferrivorans, Acidithiobacillus ferrivorans (YP_004785009); A. ambivalens, Acidianus ambivalens (P29082); A. tengchongensis, Acidianus tengchongensis (AAK58572); S. tokodaii, Sulfolobus tokodaii (NP_377053); S. thermosulfidooxidans, Sulfobacillus thermosulfidooxidans (WP_020375642).