Hairpin structures formed by alpha satellite DNA of human centromeres are cleaved by human topoisomerase IIalpha.
Although centromere function has been conserved through evolution, apparently no interspecies consensus DNA sequence exists. Instead, centromere DNA may be interconnected through the formation of certain DNA structures creating topological binding sites for centromeric proteins. DNA topoisomerase II is a protein, which is located at centromeres, and enzymatic topoisomerase II activity correlates with centromere activity in human cells. It is therefore possible that topoisomerase II recognizes and interacts with the alpha satellite DNA of human centromeres through an interaction with potential DNA structures formed solely at active centromeres. In the present study, human topoisomerase IIalpha-mediated cleavage at centromeric DNA sequences was examined in vitro. The investigation has revealed that the enzyme recognizes and cleaves a specific hairpin structure formed by alpha satellite DNA. The topoisomerase introduces a single-stranded break at the hairpin loop in a reaction, where DNA ligation is partly uncoupled from the cleavage reaction. A mutational analysis has revealed, which features of the hairpin are required for topoisomerease IIalpha-mediated cleavage. Based on this a model is discussed, where topoisomerase II interacts with two hairpins as a mediator of centromere cohesion.
Jonstrup
Anette Thyssen
AT
Department of Molecular Biology, University of Aarhus, C. F. Møllers Allé, Building 130 and Institute of Patology, University of Aarhus, Nørrebrogade 44, Aarhus, Denmark.
Thomsen
Tina
T
Wang
Yong
Y
Knudsen
Birgitta R
BR
Koch
Jørn
J
Andersen
Anni H
AH
D000951:Antigens, Neoplasm / Q000378:metabolism*; D001483:Base Sequence; D002503:Centromere / Q000737:chemistry*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004276:DNA, Satellite / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D013713:Teniposide / Q000494:pharmacology; D059005:Topoisomerase II Inhibitors
D000951:Antigens, Neoplasm; D004276:DNA, Satellite; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D059005:Topoisomerase II Inhibitors; D013713:Teniposide; D004250:DNA Topoisomerases, Type II