Nucleotide excision repair in nuclear extracts from Xenopus oocytes.

Abstract

Limited nucleotide excision repair (NER) requires at least {approx}40 proteins in extracts from purified proteins, although perhaps hundreds of proteins may influence DNA repair in cells. For efficient DNA repair in extracts, it is important to utilize a system containing large quantities of active DNA repair proteins uncontaminated with nonspecific nucleases. Unlike extracts from mammalian cells that repair {approx}2% of the input DNA, both injected Xenopus oocytes and oocyte nuclear extracts can repair {approx}100% of the input damaged DNA by NER with little or no synthesis on undamaged control substrate. Repair activity in extracts can be inactivated with antibodies and/or inhibitors, and then repair can be restored by addition of exogenous proteins. A further advantage of the Xenopus system is that results obtained from injection experiments in living cells can be compared to results obtained in nuclear extracts.