Functional domains within FEN-1 and RAD2 define a family of structure-specific endonucleases: implications for nucleotide excision repair.

Abstract

Structure-specific nucleases catalyze critical reactions in DNA replication, recombination, and repair. Recently, a structure-specific endonuclease, FEN-l, has been purified and shown to cleave DNA flap structures. Here, we describe the cloning of the murine FEN-1 gene. The nucleotide sequence of FEN-I is highly homologous to the 8accharomyces cerevisiae genes YKL510 and RAD2. We show that YKLS10 and a truncated RAD2 protein are also structure-specific endonucleases. The substrate specificity of the truncated RAD2 protein implicates branched DNA structures as important intermediates in nucleotide excision repair. The polarity of these branched DNA structures allows us to predict the placement of DNA scissions by RAD2 and RAD1/RADI0 in this reaction.

The rad18 Gene of Schizosaccharomyces pombe Defines a New Subgroup of the SMC Superfamily Involved in DNA Repair

“…rhp51 (21,29,46) is the S. pombe homolog of S. cerevisiae RAD51 which is thought to be involved in homologous pairing during recombination (52). Mammalian homologs of S. pombe rad2, and by implication rad2 itself, encode a structure-specific nuclease involved in DNA replication and/or repair (16,31,38;see Discussion). The responses to UV of the double mutants fell into two clearly different categories.…”

“…This is a likely candidate for initiating the process. The mammalian highly conserved homolog of rad2 (16, 31) encodes a structurespecific endonuclease, called FEN-1, whose preferred substrate is a ''flap'' structure (15,16). This protein is also identical to the enzyme DNase IV (38), first isolated by Lindahl (25).…”

Biochemistry and genetics of eukaryotic mismatch repair.

“…Additional genetic analysis of R THl (RAD27) has indicated that RTHl (RAD27) plays a role in repair of other types of DNA damage, that RTHl (RAD27) is a member of the RAD6 epistasis group that functions in DNA damage tolerance, and that rthl (rad27) mutants also have a cell cycle defect (Reagan et al 1995;Vallen and Cross 1995). Studies of the S. cerevisiae (called RTH1, RAD27, YKL510) and human (called FEN-1, MF-1, exonuclease IV) protein have suggested that RTHl functions in the processing of 5' ends of Okazaki fragments and processing branched DNA structures formed by different DNA repair pathways (Ishimi et al 1988;Harrington and Lieber 1994;Hiraoka et al 1995;Sommers et al 1995). There are several possible interpretations of the data on RTHl with regard to a possible role in mismatch repair.…”

XPG: Its Products and Biological Roles

“…13,14 Biochemical properties of the XPG protein Analysis of the primary sequence of XPG quickly revealed that it harbors two nuclease domains placing it in the Fen1 family of structure-specific endonucleases. 9,15 Consistent with this observation XPG was shown to be a structure specific endonuclease that cleaves substrates with the polarity that would be required for the incision 3' to the lesion in NER. 15,16 XPG cleaves a variety of substrates that contain a ss/dsDNA junction, including splayed arm and bubble substrates, which contain a 5' single-stranded overhang.…”

“…9,15 Consistent with this observation XPG was shown to be a structure specific endonuclease that cleaves substrates with the polarity that would be required for the incision 3' to the lesion in NER. 15,16 XPG cleaves a variety of substrates that contain a ss/dsDNA junction, including splayed arm and bubble substrates, which contain a 5' single-stranded overhang. 17,18 At the primary sequence level, XPG shares two conserved regions, the N and I regions, with other nucleases (Figure 1).…”