title: Endonuclease IV enhances base excision repair of endonuclease III from Methanobacterium thermoautotrophicum.
abstract: Damaged DNA strands are repaired by base excision (BER) in organisms, a process initiated by repair enzymes, which include DNA glycosylases and endonucleases. We expressed and characterized two putative endonuclease genes from Methanobacterium thermoautotrophicum, Mt0764 and Mt1010, encoding homologues of endonuclease III (endo III) and endonuclease IV (endo IV) of Escherichia coli. The Mt0764 and Mt1010 proteins showed endo III activity by removing thymine glycol from DNA strand and AP endonuclease activity, respectively. The Mt0764 protein not only cleaved the oligonucleotide duplex, containing a thymine glycol/adenine pair efficiently, but also showed activity on the 8-oxoguanine-containing oligonucleotide duplex. In this study, we report upon the stimulation of endo III activity by endo IV using two recombinant proteins (Mt1010 and Mt0764) from M. thermoautotrophicum. Mt1010 stimulated the DNA glycosylase activity of Mt0764 for DNA substrates containing 8-oxoguanine residues and increasing the formation of the Mt0764 protein-DNA complex. The interaction between Mt1010 and Mt0764 was observed by using an in vitro binding assay. These results suggest that association between endo III and endo IV may occur in vivo, and this contributes to efficient base excision repair for the oxidative damage of DNA.
authors.affiliation: Structural Biology Research Center, Korea Institute of Science and Technology, P. O. Box 131, Cheongryang, Seoul, South Korea.
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Back
authors.forename: Ji Hyung
authors.initials: JH
authors.lastname: Chung
authors.forename: Young In
authors.initials: YI
authors.lastname: Park
authors.forename: Key-Sun
authors.initials: KS
authors.lastname: Kim
authors.forename: Ye Sun
authors.initials: YS
authors.lastname: Han
mesh_terms: D000595:Amino Acid Sequence; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D004260:DNA Repair; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000235:genetics*; D043223:Deoxyribonuclease IV (Phage T4-Induced) / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000235:genetics*; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry; D017014:Methanobacterium / Q000235:genetics*; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D013941:Thymine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D011994:Recombinant Proteins; C029389:thymine glycol; D012965:Sodium Chloride; C024829:8-hydroxyguanine; D006147:Guanine; D004247:DNA; D043223:Deoxyribonuclease IV (Phage T4-Induced); D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; D013941:Thymine; D010100:Oxygen