Fig. 4: Cryo-EM structures capture intermediate states of bEBP ATP hydrolysis.
a Conserved “GAFTGA” loops at the bEBP pore (top panel) engage with σN-RI and arrange in a spiral pattern (bottom panel; residues 209–224 of each bEBP subunit and residues 3–15 of σN-RI are shown). Map density for σN-RI (sharpened map) shown as transparent surface (orange). The small inset shows a schematic representation. b Clipped surface representation of bEBP subunits reveals captured side chains of σN-RI in hydrophobic pockets. Pocket-forming residues are shown in stick representation. Subunits a and f are hidden for visual clarity. c Open and closed ring states correspond to ATP- and ADP-bound states of subunit e. ATP colored in red, ADP colored in gray. The C-terminal domain of subunit e extends below the plane of the hexamer in the ATP-bound state (right), but swings into the plane of the ring in the ADP-bound state (left). Small insets indicate conformational change of subunit f schematically. d Active site interactions in subunit e show ATP coordination in a pre-catalytic state (left panel; open ring). Closed ring state contains ADP in the active site of subunit e, corresponding to a post-catalytic state. The arginine finger (R299, f) moved out of the active site (black arrow), and intersubunit salt bridge between E174 (e) and R253 (f) is broken. S-I = sensor I; S-II = sensor II.
