Translesion Synthesis Past the C8- and <i>N</i><sup>2</sup>-Deoxyguanosine Adducts
of the Dietary Mutagen 2-Amino-3-methylimidazo[4,5-<i>f</i>]quinoline in
the <i>Nar</i>I Recognition Sequence by Prokaryotic DNA Polymerases
James S. Stover
Goutam Chowdhury
Hong Zang
F. Peter Guengerich
Carmelo J. Rizzo
10.1021/tx0601455.s001
https://acs.figshare.com/articles/journal_contribution/Translesion_Synthesis_Past_the_C8_and_i_N_i_sup_2_sup_Deoxyguanosine_Adducts_of_the_Dietary_Mutagen_2_Amino_3_methylimidazo_4_5_i_f_i_quinoline_in_the_i_Nar_i_I_Recognition_Sequence_by_Prokaryotic_DNA_Polymerases/3047194
2-Amino-3-methylimidazo[4,5-<i>f</i>]quinoline (IQ) is found in cooked meats and forms DNA adducts at
the C8- and <i>N</i><sup>2</sup>-positions of dGuo after appropriate activation. IQ is a potent inducer of frameshift mutations
in bacteria and is carcinogenic in laboratory animals. We have incorporated both IQ-adducts into the G<sub>1</sub>-
and G<sub>3</sub>-positions of the <i>Nar</i>I recognition sequence (5‘-G<sub>1</sub>G<sub>2</sub>CG<sub>3</sub>CC-3‘), which is a hotspot for arylamine
modification. The in vitro replication of the oligonucleotides was examined with <i>Escherichia coli</i> pol I
Klenow fragment exo<sup>-</sup>, <i>E. coli</i> pol II exo<sup>-</sup>, and <i>Sulfolobus solfataricus</i> P2 DNA polymerase IV (Dpo4),
and the extension products were sequenced by tandem mass spectrometry. Replication of the C8-adduct
at the G<sub>3</sub>-position resulted in two-base deletions with all three polymerases, whereas error-free bypass
and extension was observed at the G<sub>1</sub>-position. The <i>N</i><sup>2</sup>-adduct was bypassed and extended by all three
polymerases when positioned at the G<sub>1</sub>-position, and the error-free product was observed. The <i>N</i><sup>2</sup>-adduct
at the G<sub>3</sub>-position was more blocking and was bypassed and extended only by Dpo4 to produce an error-free product. These results indicate that the replication of the IQ-adducts of dGuo is strongly influenced
by the local sequence and the regioisomer of the adduct. These results also suggest a possible role for
pol II and IV in the error-prone bypass of the C8-IQ-adduct leading to frameshift mutations in reiterated
sequences, whereas noniterated sequences result in error-free bypass.
2006-11-20 00:00:00
tandem mass spectrometry
dGuo
Dpo
1G
noniterated sequences result
extension
frameshift mutations
Escherichia coli pol
Sulfolobus solfataricus P 2 DNA polymerase IV
NarI Recognition Sequence
forms DNA adducts
IQ
II
replication
exo