title: Biochemical characterization of metnase's endonuclease activity and its role in NHEJ repair.
abstract: Metnase (SETMAR) is a SET-transposase fusion protein that promotes nonhomologous end joining (NHEJ) repair in humans. Although both SET and the transposase domains were necessary for its function in DSB repair, it is not clear what specific role Metnase plays in the NHEJ. In this study, we show that Metnase possesses a unique endonuclease activity that preferentially acts on ssDNA and ssDNA-overhang of a partial duplex DNA. Cell extracts lacking Metnase poorly supported DNA end joining, and addition of wt-Metnase to cell extracts lacking Metnase markedly stimulated DNA end joining, while a mutant (D483A) lacking endonuclease activity did not. Given that Metnase overexpression enhanced DNA end processing in vitro, our finding suggests a role for Metnase's endonuclease activity in promoting the joining of noncompatible ends.
authors.affiliation: Department of Biochemistry & Molecular Biology, Indiana University Simon Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Beck
authors.forename: Sung-Sook
authors.initials: SS
authors.lastname: Lee
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Williamson
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hromas
authors.forename: Suk-Hee
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000818:Animals; D001483:Base Sequence; D002457:Cell Extracts; D053837:DNA Cleavage; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D013379:Substrate Specificity
chemical_list: D002457:Cell Extracts; D004277:DNA, Single-Stranded; D011495:Histone-Lysine N-Methyltransferase; C510450:SETMAR protein, human; D003850:Deoxyribonuclease I