title: Interrogation of Base Pairing of the Spiroiminodihydantoin Diastereomers Using the α-Hemolysin Latch.
abstract: Spiroiminodihydantoin (Sp) is a hyperoxidized form of guanine (G) resulting from oxidation by reactive oxygen species. The lesion is highly mutagenic, and the stereocenter renders the two isomers with distinct behaviors in chemical, spectroscopic, enzymatic, and computational studies. In this work, the α-hemolysin (αHL) latch sensing zone was employed to investigate the base pairing properties of the Sp diastereomers embedded in a double-stranded DNA. Duplexes containing (S)-Sp consistently gave deeper current blockage, and a baseline resolution of ∼0.8 pA was achieved between (S)-Sp:G and (R)-Sp:G base pairs. Ion fluxes were generally more hindered when Sp was placed opposite pyrimidines. Analysis of the current noise of blockade events further provided dynamics information about the Sp-containing base pairs. In general, base pairs comprised of (S)-Sp generated current fluctuations larger than those of their (R)-Sp counterparts, suggesting enhanced base pairing dynamics. The current noise was also substantially affected by the identity of the base opposite Sp, increasing in the following order: A < G < T < C. This report provides information about the dynamic structure of Sp in the DNA duplex and therefore has implications for the enzymatic repair of the Sp diastereomers.
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States.
authors.forename: Tao
authors.initials: T
authors.lastname: Zeng
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States.
authors.forename: Aaron M
authors.identifier: 0000-0002-2000-0310
authors.initials: AM
authors.lastname: Fleming
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States.
authors.forename: Yun
authors.identifier: 0000-0002-6624-0934
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States.
authors.forename: Henry S
authors.identifier: 0000-0002-5053-0996
authors.initials: HS
authors.lastname: White
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States.
authors.forename: Cynthia J
authors.identifier: 0000-0001-7253-8529
authors.initials: CJ
authors.lastname: Burrows
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D020029:Base Pairing; D001692:Biological Transport; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008564:Membrane Potentials; D009838:Oligodeoxyribonucleotides / Q000737:chemistry* / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D013141:Spiro Compounds / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D008051:Lipid Bilayers; D009838:Oligodeoxyribonucleotides; D010713:Phosphatidylcholines; D013141:Spiro Compounds; C408822:spiroiminodihydantoin; C021091:staphylococcal alpha-toxin; D006151:Guanosine; C021016:1,2-diphytanoylphosphatidylcholine; D004247:DNA