Fig. 1.

Overall structures of IniA. a Scheme showing the domains of IniA in different colors. Secondary structure elements that form HBs are labeled. N, N-terminus; C, C-terminus. b Cartoon structure of GTP-bound IniA. As in (a), the GTPase, HB1/Neck, and HB2/Trunk domains and LI loop are colored pink, orange, green, and blue, respectively. GTP and tartaric acid (TA) are shown as red and magenta sticks. Mg²⁺ is represented by a green sphere. The disordered segment in the α9-loop is denoted by a dotted line. c Structural superposition of the apo IniA and GTP-bound IniA. GTP is shown as spheres. d Structural comparison of the apo structures between IniA and BDLP (PDB code: 2J69) (upper panel), and the GTP/GMPPNP-bound structures between IniA and BDLP (PDB code: 2W6D) (lower panel)