title: Purification and characterization of a novel UV lesion-specific DNA glycosylase/AP lyase from Bacillus sphaericus.
abstract: The purification and characterization of a pyrimidine dimer-specific glycosylase/AP lyase from Bacillus sphaericus (Bsp-pdg) are reported. Bsp-pdg is highly specific for DNA containing the cis-syn cyclobutane pyrimidine dimer, displaying no detectable activity on oligonucleotides with trans-syn I, trans-syn II, (6-4), or Dewar photoproducts. Like other glycosylase/AP lyases that sequentially cleave the N--glycosyl bond of the 5' pyrimidine of a cyclobutane pyrimidine dimer, and the phosphodiester backbone, this enzyme appears to utilize a primary amine as the attacking nucleophile. The formation of a covalent enzyme-DNA imino intermediate is evidenced by the ability to trap this protein-DNA complex by reduction with sodium borohydride. Also consistent with its AP lyase activity, Bsp-pdg was shown to incise an AP site-containing oligonucleotide, yielding beta- and delta-elimination products. N-terminal amino acid sequence analysis of this 26 kDa protein revealed little amino acid homology to any previously reported protein. This is the first report of a glycosylase/AP lyase enzyme from Bacillus sphaericus that is specific for cis-syn pyrimidine dimers.
authors.affiliation: School of Medicine, The University of Texas Medical Branch at Galveston, 77555, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Vasquez
authors.forename: S G
authors.initials: SG
authors.lastname: Nyaga
authors.forename: R S
authors.initials: RS
authors.lastname: Lloyd
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D001483:Base Sequence; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004249:DNA Damage; D045647:DNA Glycosylases; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011740:Pyrimidine Dimers / Q000378:metabolism / Q000528:radiation effects; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014466:Ultraviolet Rays
chemical_list: D004269:DNA, Bacterial; D011740:Pyrimidine Dimers; D043223:Deoxyribonuclease IV (Phage T4-Induced); D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase