Figure 3
Structural homologs of Mt-DsbA and sequence alignment. Structures in panels A-E are shown in cartoon representation with the CXXC (designated with a red arrow) and structural disulfide bond (designated with a green circle) shown in stick representation with sulfur atoms color in yellow. The blue circle represents the Ca2+-binding site of Bs-BdbD and the red circles represent the distinct structural differences between the DsbA-like proteins. A. Mtb DsbA (Mt-DsbA, PDB ID: 4IHU) colored in blue B. B. subtilis BdbD ( Bs-BdbD, PDB ID: 3EU3, [30]) colored in pink C. E. coli DsbA (Ec-DsbA, PDB ID: 1DSB, [40]) colored in green D. W. pipientis α-DsbA (Wp-DsbA, PDB ID: 3F4T, [42]) colored in orange, E. S. aureus DsbA (Sa-DsbA, PDB ID: 3BCI, [31]) colored in yellow F. Superimposition of Mt-DsbA with the other four DsbA homologs in ribbon representation. G. Overall sequence and structural comparison of Mt-DsbA, Bs-BdbD, Sa-DsbA, Wp-DsbA and Ec-DsbA. The sequences are less than 20% identical and the conserved CXXC and cis-Pro loop motifs are highlighted in blue. Boxed regions correspond to insertions that contribute to structural differences in the respective homolog sequence, red for Mt-DsbA and green for Ec-DsbA. Secondary-structure elements for Mt-DsbA are depicted on the top line.