title: Purification and characterization of the Saccharomyces cerevisiae RAD1/RAD10 endonuclease.
abstract: The Saccharomyces cerevisiae RAD1 and RAD10 genes are required for the incision step of excision repair, and in addition, they function in mitotic recombination. The RAD1 and RAD10 proteins are associated in a tight complex, and genetic studies have indicated that complex formation is essential for the RAD1/RAD10 controlled biological activities. We had previously purified the RAD10 protein to near homogeneity from yeast and shown that it is a DNA-binding protein with a strong preference for single-stranded DNA. In this study, we purify the RAD1 protein to near homogeneity from yeast and show that it also binds single-stranded DNA preferentially and that the RAD1/RAD10 complex possesses an endonuclease activity. We characterize the RAD1/RAD10 endonuclease activity on both single-stranded and double-stranded DNAs, using agarose gel electrophoresis and trichloroacetic acid precipitation. The RAD1/RAD10 nuclease exhibits a much higher level of activity on single-stranded DNA than double-stranded DNA. The susceptibility of double-stranded DNA to nicking by the RAD1/RAD10 enzyme is markedly dependent on the degree of negative superhelicity, such that a 15-fold increase in nicking rate is observed from superhelical state sigma = zero to sigma = -0.08. The enzyme produces 3'-hydroxyl and 5'-phosphate termini on both single- and double-stranded DNAs. We discuss the role of RAD1/RAD10 endonuclease in nucleotide excision repair and in mitotic recombination.
authors.affiliation: Department of Biology, University of Rochester, New York 14642.
authors.forename: P
authors.initials: P
authors.lastname: Sung
authors.forename: P
authors.initials: P
authors.lastname: Reynolds
authors.forename: L
authors.initials: L
authors.lastname: Prakash
authors.forename: S
authors.initials: S
authors.lastname: Prakash
mesh_terms: D002852:Chromatography, Ion Exchange; D004249:DNA Damage; D045643:DNA Repair Enzymes; D004271:DNA, Fungal / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004720:Endonucleases / Q000302:isolation & purification* / Q000378:metabolism; D005656:Fungal Proteins / Q000302:isolation & purification* / Q000378:metabolism; D009690:Nucleic Acid Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D015719:Single-Strand Specific DNA and RNA Endonucleases; D014466:Ultraviolet Rays
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D004720:Endonucleases; C069266:RAD1 protein, S cerevisiae; C064162:RAD10 protein, S cerevisiae; D015719:Single-Strand Specific DNA and RNA Endonucleases; D045643:DNA Repair Enzymes