8-(Hydroxymethyl)-3,N4-etheno-C, a potential carcinogenic glycidaldehyde product, miscodes in vitro using mammalian DNA polymerases

B. Singer, Michael Medina, Yanbin Zhang, Zhigang Wang, Anton B. Guliaev, Bo Hang

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

8-(Hydroxymethyl)-3,N4-etheno-C (8-HM-εC) is an exocyclic adduct resulting from the reaction of dC with glycidaldehyde, a mutagen and animal carcinogen. This compound has now been synthesized and its phosphoramidite incorporated site-specifically into a defined 25-mer oligonucleotide. In this study, the mutagenic potential of this adduct in the 25-mer oligonucleotide was investigated in an in vitro primertemplate extension assay using four mammalian DNA polymerases. The miscoding potentials were also compared to those of an analogous derivative, 3,N4-etheno C (εC), in the same sequence. Both adducts primarily blocked replication by calf thymus DNA polymerase α at the modified base, while human polymerase β catalyzed measurable replication synthesis through both adducts. Nucleotide insertion experiments showed that dA and dC were incorporated by pol β opposite either adduct, which would result in a C → T transition or C → G transversion. Human polymerase η, a product of the xeroderma pigmentosum variant (XP-V) gene, catalyzed the most efficient bypass of the two lesions with 25% and 32% for 8-HM-εC and εC bypassed after 15 min. Varying amounts of all four bases opposite the modified bases resulted with pol η. Human polymerase κ primarily blocked synthesis at the base prior to the adduct. However, some specific misincorporation of dT resulted, forming an εC·T or 8-HM-EC·T pair. From these data, we conclude that the newly synthesized glycidaldehyde-derived adduct, 8-HM-εC, is a miscoding lesion. The bypass efficiency and insertion specificity of 8-HM-εC and εC were similar for all four polymerases tested, which could be attributed to the similar planarity and sugar conformations for these two derivatives as demonstrated by molecular modeling studies.

Original languageEnglish
Pages (from-to)1778-1785
Number of pages8
JournalBiochemistry
Volume41
Issue number6
DOIs
StatePublished - Feb 12 2002

ASJC Scopus subject areas

  • Biochemistry

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