biostudies-literatureUnknown26(4)Abdurashidova GThe human DNA replication origin, located in the lamin B2 gene, interacts with the DNA topoisomerases I and II in a cell cycle-modulated manner. The topoisomerases interact in vivo and in vitro with precise bonds ahead of the start sites of bidirectional replication, within the pre-replicative complex region; topoisomerase I is bound in M, early G1 and G1/S border and topoisomerase II in M and the middle of G1. The Orc2 protein competes for the same sites of the origin bound by either topoisomerase in different moments of the cell cycle; furthermore, it interacts on the DNA with topoisomerase II during the assembly of the pre-replicative complex and with DNA-bound topoisomerase I at the G1/S border. Inhibition of topoisomerase I activity abolishes origin firing. Thus, the two topoisomeraseThe EMBO journal998-1009https://www.ebi.ac.uk/biostudies/studies/S-EPMC1852844biostudies-literatureFunctional interactions of DNA topoisomerases with a human replication origin.PMC1852844Sandoval ODanailov MBAbdurashidova GBiamonti GRadulescu SRiva SZahariev SDemidovich ASantamaria LFalaschi AfalseFunctional interactions of DNA topoisomerases with a human replication origin.The human DNA replication origin, located in the lamin B2 gene, interacts with the DNA topoisomerases I and II in a cell cycle-modulated manner. The topoisomerases interact in vivo and in vitro with precise bonds ahead of the start sites of bidirectional replication, within the pre-replicative complex region; topoisomerase I is bound in M, early G1 and G1/S border and topoisomerase II in M and the middle of G1. The Orc2 protein competes for the same sites of the origin bound by either topoisomerase in different moments of the cell cycle; furthermore, it interacts on the DNA with topoisomerase II during the assembly of the pre-replicative complex and with DNA-bound topoisomerase I at the G1/S border. Inhibition of topoisomerase I activity abolishes origin firing. Thus, the two topoisomerase2007-01-01T00:00:00Z2007 Feb2026-07-09T11:00:50.96Z2026-07-09T10:31:49.835ZS-EPMC18528441729021610.1038/sj.emboj.7601578