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  • Replication-Dependent Unhooking of DNA Interstrand Cross-Links by the NEIL3 Glycosylase.

Replication-Dependent Unhooking of DNA Interstrand Cross-Links by the NEIL3 Glycosylase.

Cell (2016-10-04)
Daniel R Semlow, Jieqiong Zhang, Magda Budzowska, Alexander C Drohat, Johannes C Walter
ABSTRACT

During eukaryotic DNA interstrand cross-link (ICL) repair, cross-links are resolved ("unhooked") by nucleolytic incisions surrounding the lesion. In vertebrates, ICL repair is triggered when replication forks collide with the lesion, leading to FANCI-FANCD2-dependent unhooking and formation of a double-strand break (DSB) intermediate. Using Xenopus egg extracts, we describe here a replication-coupled ICL repair pathway that does not require incisions or FANCI-FANCD2. Instead, the ICL is unhooked when one of the two N-glycosyl bonds forming the cross-link is cleaved by the DNA glycosylase NEIL3. Cleavage by NEIL3 is the primary unhooking mechanism for psoralen and abasic site ICLs. When N-glycosyl bond cleavage is prevented, unhooking occurs via FANCI-FANCD2-dependent incisions. In summary, we identify an incision-independent unhooking mechanism that avoids DSB formation and represents the preferred pathway of ICL repair in a vertebrate cell-free system.

MATERIALS
Product Number
Brand
Product Description

Roche
Random Primed DNA Labeling Kit