FtsA and crenactin filament bending and twisting are driven by changes to subunit dihedral angles.

(A) Illustration of the two possible axes for FtsA dimer bending. (B) The dihedral angle of the bottom subunit in an FtsA-ATP dimer was highly correlated with bending angle θ2 in all unconstrained simulations. (C) Steering the dihedral angle (φ) of the bottom subunit of an FtsA-ATP dimer from 16.4° to 29.6° caused systematic shifts in the bending angle θ2. Curves are Gaussian fits to the data. Dashed lines are mean values. (D) Illustration of the large degree of twist in a crenactin dimer. (E) The dihedral angle (φ) of the bottom subunit in a crenactin-ATP dimer was highly correlated with dimer twist in unconstrained simulations. (F) Steering the dihedral angle of the bottom subunit of a crenactin-ATP dimer from 22.6° to 26.7° caused a systematic shift in dimer twist. Curves are Gaussian fits to the data. Dashed lines are mean values.