10.1021/tx0601455.s001
James S. Stover
James S.
Stover
Goutam Chowdhury
Goutam
Chowdhury
Hong Zang
Hong
Zang
F. Peter Guengerich
F. Peter
Guengerich
Carmelo J. Rizzo
Carmelo J.
Rizzo
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
American Chemical Society
2006
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
2006-11-20 00:00:00
Journal contribution
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.