Nucleotide Excision Repair Coupled to Chromatin Assembly

The packaging of DNA into a chromatin structure within the eukaryotic nucleus can affect processes such as DNA replication, transcription, recombination and repair. During nucleotide excision repair (NER), a major DNA repair pathway, rearrangements of the nucleosomal organisation are observed (). These rearrangements can be envisioned as the rapid succession of disassembly and reassembly events. A tight co-ordination between the actual DNA repair event and the chromatin assembly process will be critical to fully restore a functional genome. A step toward the dissection of these events was recently accomplished by the development of an assay for both chromatin assembly and NER on the same DNA molecules in cell-free systems competent for the two processes (,). Both chromatin assembly and NER have been independently analysed in a variety of cell-free systems. Efficient chromatin assembly can be reproduced in crude extracts derived from Xenopus oocytes or eggs (, , , ), Drosophila embryos (, , ), or from human cells (, , , ). Extracts competent for the NER process can be derived from a variety of cultured mammalian cells (,), cultured Drosophila cells (), and Xenopus eggs ().