Fig. 5: A potential redox regulatory mechanism unique to AsfvTop2.

a, b The close-up view for the relative positions of MgAMP-PNP and the essential residues (C72, C138, H68, H73, and D137, all in stick presentation) involved in the potential regulatory mechanism. The reduced (a) and oxidized (b) forms are shown in cyan and pale cyan cartoon presentations, respectively. The disulfide bond between C72 and C138 is shown in brown stick. D137 and C138 are located at a long-extended surface loop (colored in blue) that harbors the active site residues interacting with the triphosphate group of the AMP-PNP. The segment E69-H73 that moves to form the disulfide bond is shown in red. c Analysis of ATP hydrolysis for the AsfvTop2 ATPase domain in the presence of 1 mM ATP and varying concentrations of the enzyme. The y-axis shows the specific activity from each measurement. Raw data are provided in Supplementary Data 5. d C72A mutation of the full-length AsfvTop2 resulted in significant reduction of DNA decatenation activity in comparison to the wild type over different time points. Detailed conditions are described in Supplementary Fig. 13c, d. Raw data are provided in Supplementary Data 6. Each data point in panels c, d includes the mean ± SE value from three independent reactions (n = 3) from the same batch of sample. Similar assay methods for ATPase and decatenation activities have been used previously for other Top2 proteins^35,83. e A graphical summary illustrating that the enzyme-substrate recognition is mediated by the joint application of the substrate binding theories in order: (1) catalytic selection, (2) conformational selection, and (3) induced fit. The catalytic selection should be replaced by functional selection when referring to other functions instead of catalysis.