Fig. 6.

Protofilaments of actin-like fold. (A)–(C) Superposition of actin (domain-wise colours; PDB ID 3MFP) with proteins of the actin-fold (grey), namely ParM [A; PDB ID 4A62], MreB [B; PDB ID 1JCG; (van den Ent et al., 2001)] and FtsA [C; PDB ID 4A2A; (Szwedziak et al., 2012)], with available subnanometer resolution structures of the protofilaments. C-alpha residues of domain IIA (corresponding to subdomain 3 of actin) were used for obtaining the superposition. (D)–(E) Two views of the protofilaments of actin, ParM, MreB and FtsA, with the middle subunit as reference. The superpositions of the middle subunit are shown in (A)–(C). The variation in twist/handedness of the protofilaments despite the similarities between the interfaces is highlighted.