Fig. 3. Structural characterization of MsSepF_core.

a Crystal structure of the MsSepF dimer composed of two identical monomers, color-coded according to secondary structure (helices, green; strands, yellow). Each protomer consists of a 5-stranded β-sheet flanked by 2 α-helices and a helical turn (η1). In each protomer, the C-terminal strand β5 (in purple) forms part of the opposing β-sheet. b Comparison of functional SepF dimer interfaces in Bacteria and Archaea, as defined by the complexes with FtsZ. The α interface has only been found in the crystal structures of bacterial SepF dimers such as those of C. glutamicum (PDB 6SCP, shown in the figure) and B. subtilis (PDB 3ZIH), whereas the β interface has been found in all Archaeal structures (e.g. Archaeoglobus fulgidus (PDB: 3ZIE), Pyrococcus furiosus (PDB: 3ZIG), see also Supplementary Fig. 8). The C-terminal secondary structure element of the crystal structures (β5 in M. smithii and α3 in C. glutamicum) are depicted in purple.