Fig. 1

PilT from G. metallireducens (PilT^Gm) crystallizes in multiple conformations. Individual packing units (N2Dⁿ and CTDⁿ⁺¹) are uniquely colored. A smoothed transparent surface representation of the main chain is shown. The ligand bound in the nucleotide-binding site is shown in stick representation. a, c, e, g, j Top and side views of unique PilT^Gm crystal structures. O and C denote open and closed interfaces, respectively. b, d, f, h, k Correspond to the hexamers shown above and show a cross section of the closed- and open interfaces on the top and bottom panels, respectively. Select side chains discussed in the text are shown for reference. 2|F_O|−|F_c| maps are shown as a mesh with I/σ(I) levels of 2 with the exception of (d) where 1.5 was used. a, b Crystal structure of methylated PilT^Gm in the OCOCOC conformation. c, d Crystal structure of PilT^Gm without added nucleotide in the OCOCOC conformation. e, f Crystal structure of PilT^Gm washed with ATP prior to crystallization in the OCOCOC conformation. g, h Crystal structure of PilT^Gm incubated with ATP during crystallization at pH 6.5 in the CCCCCC conformation. i In vitro ATP hydrolysis (mean ± SEM, n = 2) by PilT^Gm from pH 5.5 to 9.0. j, k Crystal structure of PilT^Gm incubated with ANP during crystallization in the CCOCCO conformation