Figure 3. Groups of Dsr-LP and Dsr.

The Dsr-LP classification (groups Ia-d and IIIa-d) is based on the presence and absence of the following functionally important sequence signatures: [Fe₄-S₄]-coupled siroheme binding site; iron sulfur cluster sites (*, peripheral; ** additional); and sulfite binding amino acid residues (Arg or Lys). Numbers 1–4 indicates the positions (1^st, 2^nd, 3^rd and 4^th) of sulfite binding amino acid residues. The amino acid sequences representing these characteristics are shown in Fig. S1. Groups IIa-d, represented by dotted-line box are hypothetical and yet to be detected.