SUMO-2/3 regulates topoisomerase II in mitosis.
We have analyzed the abundance of SUMO-conjugated species during the cell cycle in Xenopus egg extracts. The predominant SUMO conjugation products associated with mitotic chromosomes arose from SUMO conjugation of topoisomerase II. Topoisomerase II was modified exclusively by SUMO-2/3 during mitosis under normal circumstances, although we observed conjugation of topoisomerase II to SUMO-1 in extracts with exogenous SUMO-1 protein. Inhibition of SUMO modification by a dominant-negative mutant of the SUMO-conjugating enzyme Ubc9 (dnUbc9) did not detectably alter topoisomerase II activity, but it did increase the amount of unmodified topoisomerase II retained on mitotic chromosomes after high salt washing. dnUbc9 did not disrupt the assembly of condensed mitotic chromosomes or block progression of extracts through mitosis, but it did block the dissociation of sister chromatids at the metaphase-anaphase transition. Together, our results suggest that SUMO conjugation is important for chromosome segregation in metazoan systems, and that mobilization of topoisomerase II from mitotic chromatin may be a key target of this modification.
Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-5431, USA.
Yoshiaki
Y
Azuma
Alexei
A
Arnaoutov
Mary
M
Dasso
D000818:Animals; D002457:Cell Extracts; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D020090:Chromosome Segregation / Q000235:genetics; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008938:Mitosis / Q000235:genetics*; D009865:Oocytes; D011499:Protein Processing, Post-Translational / Q000235:genetics; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D002457:Cell Extracts; D002843:Chromatin; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; C492189:SUMO3 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D014452:Ubiquitins; D044763:Ubiquitin-Conjugating Enzymes; D004250:DNA Topoisomerases, Type II; D000098843:Ubiquitin-Conjugating Enzyme UBC9