Synergistic effects on mutagenicity of tandem lesions containing 8-oxo-7,8-dihydro-2'-deoxyguanosine or Fapy•dG flanked by a 3' 5-formyl-2'-deoxyuridine in human cells

Jan Henric T Bacurio; Shijun Gao; Haozhe Yang; Ashis K Basu; Marc M Greenberg

doi:10.1016/j.dnarep.2023.103527

Synergistic effects on mutagenicity of tandem lesions containing 8-oxo-7,8-dihydro-2'-deoxyguanosine or Fapy•dG flanked by a 3' 5-formyl-2'-deoxyuridine in human cells

DNA Repair (Amst). 2023 Sep:129:103527. doi: 10.1016/j.dnarep.2023.103527. Epub 2023 Jun 24.

Authors

Jan Henric T Bacurio¹, Shijun Gao², Haozhe Yang³, Ashis K Basu⁴, Marc M Greenberg⁵

Affiliations

¹ Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA.
² Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
³ Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Respiratory and Critical Care Medicine Targeted Tracer Research and Development Laboratory West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China.
⁴ Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA. Electronic address: ashis.basu@uconn.edu.
⁵ Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA. Electronic address: mgreenberg@jhu.edu.

PMID: 37467631
PMCID: PMC10528826 (available on 2024-09-01)
DOI: 10.1016/j.dnarep.2023.103527

Abstract

Modified nucleotides often hinder and/or decrease the fidelity of DNA polymerases. Tandem lesions, which are comprised of DNA modifications at two contiguous nucleotide positions, can be even more detrimental to genome stability. Recently, tandem lesions containing 5-formyl-2'-deoxyuridine (5fdU) flanked at the 5'-position by 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OxodGuo) or N-(2-deoxy-α,β-D-erythropentofuranosyl)-N-(2,6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy•dG) were discovered. We examined the replication of 5'- 8-OxodGuo-5fdU and 5'-Fapy•dG-5fdU tandem lesions in HEK 293T cells and several polymerase deficient variants by transfecting single-stranded vectors containing them. The local sequence of the tandem lesions encompasses the 273 codon of the p53 gene, a mutational hot-spot. The bypass efficiency and mutation spectra of the tandem lesions were compared to those of the isolated lesions. Replication of weakly mutagenic 5-fdU is little changed when part of the 5'- 8-OxodGuo-5fdU tandem lesion. G → T transversions attributable to 8-OxodGuo increase > 10-fold when the tandem lesion is bypassed. 5'-Fapy•dG-5fdU has a synergistic effect on the error-prone bypass of both lesions. The mutation frequency (MF) of 5'-Fapy•dG-5fdU increases 3-fold compared to isolated Fapy•dG. In addition, a 5'-adjacent Fapy•dG significantly increases the MF of 5fdU. The major mutation, G → T transversions, decrease by almost a third in hPol κ^- cells, which is the opposite effect when isolated Fapy•dG in the same sequence context is replicated in HEK 293T cells in the same sequence. Steady-state kinetics indicate that hPol κ contributes to greater G → T transversions by decreasing the specificity constant for dCTP compared to an isolated Fapy•dG. The greater conformational freedom of Fapy•dG compared to 8-OxodGuo and its unusual ability to epimerize at the anomeric center is believed to be the source of the complex effects of 5'-Fapy•dG-5fdU on replication.

Keywords: 8-Oxo-7,8-dihydro-2’-deoxyguanosine; Error-prone bypass; Fapy•dG; Mutagenicity; Tandem DNA lesions; Translesion synthesis.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

8-Hydroxy-2'-Deoxyguanosine
DNA Damage
DNA-Directed DNA Polymerase*
Deoxyguanosine
Humans
Mutagenesis
Mutagens*
Nucleotides

Substances

Mutagens
8-Hydroxy-2'-Deoxyguanosine
5-formyl-2'-deoxyuridine
DNA-Directed DNA Polymerase
Nucleotides
Deoxyguanosine

Abstract

Publication types

MeSH terms

Substances

Grants and funding