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Transient dsDNA breaks during pre-replication complex assembly.

ABSTRACT: Initiation of DNA replication involves the ordered assembly of the multi-protein pre-replicative complex (pre-RC) during G(1) phase. Previously, DNA topoisomerase II (topo II) was shown to associate with the DNA replication origin located in the lamin B2 gene locus in a cell-cycle-modulated manner. Here we report that activation of both the early-firing lamin B2 and the late-firing hOrs8 human replication origins involves DNA topo II-dependent, transient, site-specific dsDNA-break formation. Topo IIbeta in complex with the DNA repair protein Ku associates in vivo and in vitro with the pre-RC region, introducing dsDNA breaks in a biphasic manner, during early and mid-G(1) phase. Inhibition of topo II activity interferes with the pre-RC assembly resulting in prolonged G(1) phase. The data mechanistically link DNA topo IIbeta-dependent dsDNA breaks and the components of the DNA repair machinery with the initiation of DNA replication and suggest an important role for DNA topology in origin activation.

SUBMITTER: Rampakakis E

PROVIDER: S-EPMC2761281 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Transient dsDNA breaks during pre-replication complex assembly.

Rampakakis Emmanouil E Zannis-Hadjopoulos Maria M

Nucleic acids research 20090728 17

Initiation of DNA replication involves the ordered assembly of the multi-protein pre-replicative complex (pre-RC) during G(1) phase. Previously, DNA topoisomerase II (topo II) was shown to associate with the DNA replication origin located in the lamin B2 gene locus in a cell-cycle-modulated manner. Here we report that activation of both the early-firing lamin B2 and the late-firing hOrs8 human replication origins involves DNA topo II-dependent, transient, site-specific dsDNA-break formation. Top ...[more]

PMID: 19638425

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