FIGURE 6.

CdSpoIID and BaSpoIID structural superimposition. a, superimposition of BaSpoIID (in slate ribbon) on CdSpoIID (in white ribbon). b, superimposition of BaSpoIID (slate ribbon) on CdSpoIID (white ribbon). c, zoom-in on the N-terminal β-sheet of BaSpoIID and CdSpoIID (colored as in A) with the extra β3-strand of CdSpoIID anchoring the turn-β-strand-turn motif of the zinc-binding site. d, phylogenetic tree of the SpoIID family based on the 40 most divergent members. The members that have conserved residues for the zinc coordination in CdSpoIID were identified and labeled with an open circle. The solid symbols show the position of CdSpoIID and BaSpoIID. e, CdSpoIID colored according to the sequence conservation of the most 40 different SpoIID family members. The most highly conserved residues are red, and the least conserved residues are blue.