Enhancing Bulge Stabilization through Linear Extension of C8-Aryl-Guanine Adducts to Promote Polymerase Blockage or Strand Realignment to Produce a C:C Mismatch

• Published in: Chemical research in toxicology Vol. 28; no. 8; pp. 1647 - 1658
• Main Authors: Sproviero, Michael, Verwey, Anne M. R, Witham, Aaron A, Manderville, Richard A, Sharma, Purshotam, Wetmore, Stacey D
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 17.08.2015; Amer Chemical Soc
• Subjects: Base Pair Mismatch; Chemistry; Chemistry, Medicinal; Chemistry, Multidisciplinary; DNA Adducts - chemistry; DNA Sequence, Unstable; DNA-Directed DNA Polymerase - metabolism; Enzyme Stability; Guanine - chemistry; Life Sciences & Biomedicine; Pharmacology & Pharmacy; Physical Sciences; Science & Technology; Sequence Alignment; Sulfolobus solfataricus; Toxicology; FAMILY DNA-POLYMERASE; FOOD MUTAGEN; FRAMESHIFT MUTAGENESIS; OPPOSITE DC; RADICAL-CATION; ENERGETIC CHARACTERIZATION; NARI RECOGNITION SEQUENCE; CONFORMATIONAL PREFERENCES; NUCLEIC-ACID ADDUCTS; DIETARY MUTAGEN
• ISSN: 0893-228X; 1520-5010
• DOI: 10.1021/acs.chemrestox.5b00233

Aryl radicals can react at the C8-site of 2′-deoxyguanosine (dG) to produce DNA adducts with a C8–C linkage (denoted C-linked). Such adducts are structurally distinct from those possessing a flexible amine (N-linked) or ether (O-linked) linkage, which separates the C8-aryl moiety from the guanine nucleobase. In the current study, two model C-linked C8-dG adducts, namely, C8-benzo­[b]­thienyl-dG ([BTh]­G) and C8-(pyren-1-yl)-dG ([Py]­G), were incorporated into the NarI (12mer, NarI­(12) and 22mer, NarI­(22)) hotspot sequence for frameshift mutations in bacteria. For the first time, C-linked C8-dG adducts are shown to stabilize the −2 deletion duplex within the NarI sequence. Primer-elongation assays employing Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4) demonstrates the influence of C8-aryl ring size and shape in promoting Dpo4 blockage or strand realignment to produce a C:C mismatch downstream of the adduct site. Molecular dynamics simulations of the −2 deletion duplex suggest that both anti and syn adduct structures are energetically accessible. These findings provide a rationale for describing the biochemical outcome induced by C-linked C8-dG adducts when processed by Dpo4.