Fig. 8. Modeled complex between the FtsQ Arg/Ala-rich helix and monomeric or polymeric FtsZ.

a The FtsQ helix docked to the GTPase domain of FtsZ (Protein Data Bank (PDB) entry 1RQ2²²). The FtsQ helix is shown with Arg, Ala, Glu, and other residues in blue, green, red, and gray, respectively. The FtsZ GTPase domain is shown in gray, except with yellow for the H7 helix at the base of the inter-subdomain cleft and two short segments at the entrance of the cleft. b Salt bridges and hydrogen bonds between the FtsQ helix and the inter-subdomain cleft of the FtsZ GTPase domain. c The FtsQ helix docked to a GTPase domain in a curved FtsZ polymer (PDB entry 4KWE²⁶), free of clashes with neighboring GTPase domains. d The FtsQ helix docked to a GTPase domain in a straight FtsZ polymer (PDB entry 1W5A⁶⁴), clashing with neighboring GTPase domains (see inset).