Fig. 1.

Monomeric and protofilament crystal structures of ΦKZ TubZ. (a) Cartoon representation of three subunits of the ΦKZ TubZ protofilament crystal structure; bound GDP shown as spheres. (b) Coomassie-stained SDS-PAGE of ΦKZ TubZ protein; molecular weight standards are expressed in kilodaltons. (c) Cartoon representation of the crystal structure of a monomer of ΦKZ TubZ annotated with the named tubulin/FtsZ secondary structural elements;¹⁹ bound GDP shown as spheres. (d) Cartoon representation of three subunits of the ΦKZ TubZ protofilament crystal structure; bound GDP shown as spheres, rotated 180° and with the central subunit coloured grey in order to highlight the C-terminal knuckle binding site. (e) Structural alignment of the three resolved bacteriophage tubulin/FtsZs. Colour scheme for all plates: green, GTPase domain; yellow, helix 7; magenta, activation domain; cyan, C-terminal helix; nucleotide in cyan and CPK colours.