title: Expression and purification of active mouse and human NEIL3 proteins.
abstract: Endonuclease VIII-like 3 (Neil3) is one of the five DNA glycosylases found in mammals that recognize and remove oxidized bases, and initiate the base excision repair (BER) pathway. Previous attempts to express and purify the mouse and human orthologs of Neil3 in their active form have not been successful. Here we report the construction of bicistronic expression vectors for expressing in Escherichia coli the full-length mouse Neil3 (MmuNeil3), its glycosylase domain (MmuNeil3Δ324), as well as the glycosylase domain of human Neil3 (NEIL3Δ324). The purified Neil3 proteins are all active, and NEIL3Δ324 exhibits similar glycosylase/lyase activity as MmuNeil3Δ324 on both single-stranded and double-stranded substrates containing thymine glycol (Tg), spiroiminodihydantoin (Sp) or an abasic site (AP). We show that N-terminal initiator methionine processing is critical for the activity of both mouse and human Neil3 proteins. Co-expressing an E. coli methionine aminopeptidase (EcoMap) Y168A variant with MmuNeil3, MmuNeil3Δ324 and NEIL3Δ324 improves the N-terminal methionine processing and increases the percentage of active Neil3 proteins in the preparation. The purified Neil3 proteins are suitable for biochemical, structural and functional studies.
authors.affiliation: Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Stafford Hall, 95 Carrigan Dr. Burlington, VT 05405-0086, USA.
authors.forename: Minmin
authors.initials: M
authors.lastname: Liu
authors.forename: Viswanath
authors.initials: V
authors.lastname: Bandaru
authors.forename: Alicia
authors.initials: A
authors.lastname: Holmes
authors.forename: April M
authors.initials: AM
authors.lastname: Averill
authors.forename: Wendy
authors.initials: W
authors.lastname: Cannan
authors.forename: Susan S
authors.initials: SS
authors.lastname: Wallace
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D003062:Codon; D004591:Electrophoresis, Polyacrylamide Gel; D004706:Endodeoxyribonucleases / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008715:Methionine / Q000378:metabolism; D051379:Mice; D009699:N-Glycosyl Hydrolases / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D009842:Oligopeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D003062:Codon; C471213:His-His-His-His-His-His; D009842:Oligopeptides; D011993:Recombinant Fusion Proteins; D006639:Histidine; D008715:Methionine; D004706:Endodeoxyribonucleases; C540052:NEIL3 protein, mouse; D009699:N-Glycosyl Hydrolases; C468764:NEIL3 protein, human