Implications of SUMOylation in regulating the resolution of centromeric DNA. (a) Regulating the amount of catenated centromeric DNA. Active TopoIIα resolves catenated DNA at the centromere and SUMOylation reduces the activity of TopoIIα that has completed the decatenation of DNA. Without SUMOylation, overly active TopoIIα could recatenate DNA at the centromere. (b) Regulation of the timing of decatenation. TopoIIα SUMOylation keeps centromeric TopoIIα temporally inert until anaphase, when decatenation of centromeric DNA must take place. Without proper deSUMOylation of TopoIIα, decatenation of centromeric DNA will be compromised.