PIASy-dependent SUMOylation regulates DNA topoisomerase IIα activity

DNA topoisomerase II alpha (TopoII alpha) is an essential chromosome associated enzyme with activity implicated in the resolution of tangled DNA at centromeres before anaphase onset However, the regulatory mechanism of TopoII alpha activity is not understood Here, we show that PIASy mediated small ubiquitin like modifier 2/3 (SUMO2/3) modification of TopoII alpha strongly inhibits TopoII alpha decatenation activity Using mass spectrometry and biochemical analysis, we demonstrate that TopoII alpha is SUMOylated at lysine 660 (Lys660), a residue located in the DNA gate domain, where both DNA cleavage and religation take place Remarkably, loss of SUMOylation on Lys660 eliminates SUMOylation dependent inhibition of TopoII alpha, which indicates that Lys660 SUMOylation is critical for PIASy mediated inhibition of TopoII alpha activity Together, our findings provide evidence for the regulation of TopoII alpha activity on mitotic chromosomes by SUMOylation Therefore, we propose a novel mechanism for regulation of centromeric DNA catenation during mitosis by PIASy mediated SUMOylation of TopoII alpha