Origin-dependent initiation of DNA replication within telomeric sequences.
Replication of telomeres requires the action of telomerase, the semi-conservative replication machinery and the stabilization of the replication fork during passage through telomeric DNA. Whether vertebrate telomeres support initiation of replication has not been experimentally addressed. Using Xenopus cell free extracts we established a system to study replication initiation within linear telomeric DNA substrates. We show binding of TRF2 to telomeric DNA, indicating that exogenous DNA exclusively composed of telomeric repeats is recognized by shelterin components. Interaction with telomere binding proteins is not sufficient to prevent a DNA damage response. Notably, we observe regulated assembly of the pre-replicative complex proteins ORC2, MCM6 and Cdc6 to telomeric DNA. Most importantly, we detect origin-dependent replication of telomeric substrates under conditions that inhibit checkpoint activation. These results indicate that pre-replicative complexes assemble within telomeric DNA and can be converted into functional origins.
Kurth
Isabel
I
Institute for Cancer Genetics, Department of Genetics and Development and Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032, USA.
Gautier
Jean
J
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism; D018741:Replication Origin; D016615:Telomere / Q000737:chemistry*; D014981:Xenopus
D004268:DNA-Binding Proteins; D004247:DNA