Fig. 5: The hexameric spiral-to-ring transition of Abo1 is mediated by subunit and AAA1/2 domain movements.

a Rearrangement of Abo1 hexamer subunits from a spiral staircase (ATP state, bold colors) to a planar ring (ADP state, faded colors), as represented by the change in positions of AAA1 NBD α2 and α3. The two structures are superimposed by alignment at subunit A, and arrows depict the degree of movement of each subunit from the ATP to ADP state. b ATP (bold colors)-to-ADP (faded colors) structural transition of Abo1 subunit A and F. Structures are aligned by the AAA2 domain of subunit A. c Comparison of individual subunits of ATP-Abo1 (subunits A, C, and F) juxtaposed in the same configuration when aligned by AAA2. AAA1 NBD and the linker arm move away from AAA2 NBD. AAA1 NBD and AAA2 NBD centroid positions are further apart in subunits C and F by 1.2 and 4.9 Å, respectively, when compared to subunit A. The angle the two NBDs form with respect to AAA2 HBD is also shifted by 1 and 11 degrees in subunits C and F when compared to subunit A. d Superimposition of the ADP-Abo1 subunit A (which is representative of all other ADP-Abo1 subunits) onto ATP-Abo1 subunit A and F. ATP-subunit A superimposes well onto ADP-subunit, but ATP-subunit F shows a significant divergence most prominently seen in AAA1 NBD and the linker arm.