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O 4 ‐Alkylated‐2‐Deoxyuridine Repair by O 6 ‐Alkylguanine DNA Alkyltransferase is Augmented by a C5‐Fluorine Modification
Author(s) -
Sacre Lauralicia,
O'Flaherty Derek K.,
Archambault Philippe,
Copp William,
Peslherbe Gilles H.,
Muchall Heidi M.,
Wilds Christopher J.
Publication year - 2018
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201700660
Subject(s) - chemistry , deoxyuridine , alkylation , adduct , stereochemistry , thymine , uracil , dna , organic chemistry , biochemistry , catalysis
Oligonucleotides containing various adducts, including ethyl, benzyl, 4‐hydroxybutyl and 7‐hydroxyheptyl groups, at the O 4 atom of 5‐fluoro‐ O 4 ‐alkyl‐2′‐deoxyuridine were prepared by solid‐phase synthesis. UV thermal denaturation studies demonstrated that these modifications destabilised the duplex by approximately 10 °C, relative to the control containing 5‐fluoro‐2′‐deoxyuridine. Circular dichroism spectroscopy revealed that these modified duplexes all adopted a B‐form DNA structure. O 6 ‐Alkylguanine DNA alkyltransferase (AGT) from humans (hAGT) was most efficient at repair of the 5‐fluoro‐ O 4 ‐benzyl‐2′‐deoxyuridine adduct, whereas the thymidine analogue was refractory to repair. The Escherichia coli AGT variant (OGT) was also efficient at removing O 4 ‐ethyl and benzyl adducts of 5‐fluoro‐2‐deoxyuridine. Computational assessment of N1‐methyl analogues of the O 4 ‐alkylated nucleobases revealed that the C5‐fluorine modification had an influence on reducing the electron density of the O 4 −C α bond, relative to thymine (C5‐methyl) and uracil (C5‐hydrogen). These results reveal the positive influence of the C5‐fluorine atom on the repair of larger O 4 ‐alkyl adducts to expand knowledge of the range of substrates able to be repaired by AGT.