Mechanism of replication-coupled DNA interstrand crosslink repair.
DNA interstrand crosslinks (ICLs) are toxic DNA lesions whose repair occurs in the S phase of metazoans via an unknown mechanism. Here, we describe a cell-free system based on Xenopus egg extracts that supports ICL repair. During DNA replication of a plasmid containing a site-specific ICL, two replication forks converge on the crosslink. Subsequent lesion bypass involves advance of a nascent leading strand to within one nucleotide of the ICL, followed by incisions, translesion DNA synthesis, and extension of the nascent strand beyond the lesion. Immunodepletion experiments suggest that extension requires DNA polymerase zeta. Ultimately, a significant portion of the input DNA is fully repaired, but not if DNA replication is blocked. Our experiments establish a mechanism for ICL repair that reveals how this process is coupled to DNA replication.
Räschle
Markus
M
Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology, Boston, MA 02115, USA.
Knipscheer
Puck
P
Knipsheer
Puck
P
Enoiu
Milica
M
Angelov
Todor
T
Sun
Jingchuan
J
Griffith
Jack D
JD
Ellenberger
Tom E
TE
Schärer
Orlando D
OD
Walter
Johannes C
JC
D000818:Animals; D002474:Cell-Free System; D004247:DNA; D004260:DNA Repair; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
D004247:DNA; C425929:DNA polymerase zeta; D004259:DNA-Directed DNA Polymerase