Figure 2.

Structure of Av3MDO and its comparison to Pa3MDO.A, sequence alignment of Av3MDO and Pa3MDO with secondary structural elements colored in slate and gray, respectively. Curly lines, arrows, and “T” represent α-helices, β-strands, and β-turns, respectively. The iron-binding His residues are marked by blue arrows. B, structural superposition of Av3MDO (slate) and Pa3MDO (gray). Note the slight shift in His90, His92, and the iron cofactor as well as the conformational difference at the loop marked by an asterisk, which is due to a one residue deletion between residue 116 and 117 in Av3MDO. N and C mark the N- and C-termini, respectively. The superposition was performed using the “super” command in PyMOL. C, structure of the Av3MDO iron center (brown sphere) in complex with 3HPA (orange sticks) and chloride (green sphere). Dashed lines indicate H-bonding interactions.