The major, N2-gua adduct of the (+)-anti-benzo[a]pyrene diol epoxide is capable of inducing G→A and G→C, in addition to G→T, mutations

Scott A. Jelinsky, Tongming Liu, Nicholas Geacintov, Edward L. Loechler

Research output: Contribution to journalArticle

Abstract

Mutations induced by the (+)-anti-diol epoxide of benzo[a]pyrene [(+)-anti-B[a]PDE] were collected in the supF gene of the Escherichia coli plasmid pUB3. pUB3 was reacted with (+)-anti-B[a]-PDE and then either (1) transformed immediately into E. coli or (2) heated at 80°C for 10 min and then cooled prior to transformation - the latter to probe mechanism [Rodriguez & Loechler (1993) Biochemistry 32, 1759]. Qualitatively, heating did not affect the mutagenic pattern, except at the major base substitution hotspot in supF, G115, where principally G→T mutations were obtained prior to heating, while after heating, G→A and G→C mutations became statistically significantly more prevalent. Several studies have suggested that a heat-induced chemical transformation of a (+)-anti-B[a]PDE adduct at G115 (e.g., into an apurinic site) is not likely to explain the change in mutational pattern. The most likely model is that (+)-anti-B[a]P-N2-Gua is initially trapped in a metastable conformation giving principally G→T mutations, while heating induces a change to a stable conformation(s) resulting in G→T, A, and C mutations. This suggests that adduct conformational complexity is at the root of adduct mutational complexity. To investigate this model, a plasmid (B[a]P-G115-pRE1) with (+)-anti-B[a]P-N2-Gua in the G115 sequence context is constructed using adduct site-specific techniques. Following transformation of B[a]P-G115-pRE1 into E. coli (ES87) cells, targeted G115→T (59%), A (22%), and C (19%) mutations are isolated from (+)-anti-B[a]P-N2-Gua, which approximates the ratio obtained at G115 with (+)-anti-B[a]PDE itself. (+)-anti-B[a]P-N2-Gua principally induced G→T mutations in another sequence context [5′-TGC-3′; Mackay et al. (1992) Carcinogenesis 13, 1415]. Collectively, these findings demonstrate that (+)-anti-B[a]P-N2-Gua is able to induce all three base substitution mutations and that DNA sequence context can influence the qualitative pattern of mutations from (+)-anti-B[a]P-N2-Gua. Finally, it appears that (+)-anti-B[a]P-N2-Gua at G115 may be able to induce semitargeted G116→A mutations as well, although this conclusion is more tentative.

Original languageEnglish (US)
Pages (from-to)13545-13553
Number of pages9
JournalBiochemistry
Volume34
Issue number41
StatePublished - 1995

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Benzo(a)pyrene
Epoxy Compounds
Escherichia coli
Heating
Mutation
Conformations
Plasmids
Substitution reactions
Biochemistry
DNA sequences
Genes
Carcinogenesis
Hot Temperature

ASJC Scopus subject areas

  • Biochemistry

Cite this

The major, N2-gua adduct of the (+)-anti-benzo[a]pyrene diol epoxide is capable of inducing G→A and G→C, in addition to G→T, mutations. / Jelinsky, Scott A.; Liu, Tongming; Geacintov, Nicholas; Loechler, Edward L.

In: Biochemistry, Vol. 34, No. 41, 1995, p. 13545-13553.

Research output: Contribution to journalArticle

@article{6726df6d16824544acf5258db111c45d,
title = "The major, N2-gua adduct of the (+)-anti-benzo[a]pyrene diol epoxide is capable of inducing G→A and G→C, in addition to G→T, mutations",
abstract = "Mutations induced by the (+)-anti-diol epoxide of benzo[a]pyrene [(+)-anti-B[a]PDE] were collected in the supF gene of the Escherichia coli plasmid pUB3. pUB3 was reacted with (+)-anti-B[a]-PDE and then either (1) transformed immediately into E. coli or (2) heated at 80°C for 10 min and then cooled prior to transformation - the latter to probe mechanism [Rodriguez & Loechler (1993) Biochemistry 32, 1759]. Qualitatively, heating did not affect the mutagenic pattern, except at the major base substitution hotspot in supF, G115, where principally G→T mutations were obtained prior to heating, while after heating, G→A and G→C mutations became statistically significantly more prevalent. Several studies have suggested that a heat-induced chemical transformation of a (+)-anti-B[a]PDE adduct at G115 (e.g., into an apurinic site) is not likely to explain the change in mutational pattern. The most likely model is that (+)-anti-B[a]P-N2-Gua is initially trapped in a metastable conformation giving principally G→T mutations, while heating induces a change to a stable conformation(s) resulting in G→T, A, and C mutations. This suggests that adduct conformational complexity is at the root of adduct mutational complexity. To investigate this model, a plasmid (B[a]P-G115-pRE1) with (+)-anti-B[a]P-N2-Gua in the G115 sequence context is constructed using adduct site-specific techniques. Following transformation of B[a]P-G115-pRE1 into E. coli (ES87) cells, targeted G115→T (59{\%}), A (22{\%}), and C (19{\%}) mutations are isolated from (+)-anti-B[a]P-N2-Gua, which approximates the ratio obtained at G115 with (+)-anti-B[a]PDE itself. (+)-anti-B[a]P-N2-Gua principally induced G→T mutations in another sequence context [5′-TGC-3′; Mackay et al. (1992) Carcinogenesis 13, 1415]. Collectively, these findings demonstrate that (+)-anti-B[a]P-N2-Gua is able to induce all three base substitution mutations and that DNA sequence context can influence the qualitative pattern of mutations from (+)-anti-B[a]P-N2-Gua. Finally, it appears that (+)-anti-B[a]P-N2-Gua at G115 may be able to induce semitargeted G116→A mutations as well, although this conclusion is more tentative.",
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T1 - The major, N2-gua adduct of the (+)-anti-benzo[a]pyrene diol epoxide is capable of inducing G→A and G→C, in addition to G→T, mutations

AU - Jelinsky, Scott A.

AU - Liu, Tongming

AU - Geacintov, Nicholas

AU - Loechler, Edward L.

PY - 1995

Y1 - 1995

N2 - Mutations induced by the (+)-anti-diol epoxide of benzo[a]pyrene [(+)-anti-B[a]PDE] were collected in the supF gene of the Escherichia coli plasmid pUB3. pUB3 was reacted with (+)-anti-B[a]-PDE and then either (1) transformed immediately into E. coli or (2) heated at 80°C for 10 min and then cooled prior to transformation - the latter to probe mechanism [Rodriguez & Loechler (1993) Biochemistry 32, 1759]. Qualitatively, heating did not affect the mutagenic pattern, except at the major base substitution hotspot in supF, G115, where principally G→T mutations were obtained prior to heating, while after heating, G→A and G→C mutations became statistically significantly more prevalent. Several studies have suggested that a heat-induced chemical transformation of a (+)-anti-B[a]PDE adduct at G115 (e.g., into an apurinic site) is not likely to explain the change in mutational pattern. The most likely model is that (+)-anti-B[a]P-N2-Gua is initially trapped in a metastable conformation giving principally G→T mutations, while heating induces a change to a stable conformation(s) resulting in G→T, A, and C mutations. This suggests that adduct conformational complexity is at the root of adduct mutational complexity. To investigate this model, a plasmid (B[a]P-G115-pRE1) with (+)-anti-B[a]P-N2-Gua in the G115 sequence context is constructed using adduct site-specific techniques. Following transformation of B[a]P-G115-pRE1 into E. coli (ES87) cells, targeted G115→T (59%), A (22%), and C (19%) mutations are isolated from (+)-anti-B[a]P-N2-Gua, which approximates the ratio obtained at G115 with (+)-anti-B[a]PDE itself. (+)-anti-B[a]P-N2-Gua principally induced G→T mutations in another sequence context [5′-TGC-3′; Mackay et al. (1992) Carcinogenesis 13, 1415]. Collectively, these findings demonstrate that (+)-anti-B[a]P-N2-Gua is able to induce all three base substitution mutations and that DNA sequence context can influence the qualitative pattern of mutations from (+)-anti-B[a]P-N2-Gua. Finally, it appears that (+)-anti-B[a]P-N2-Gua at G115 may be able to induce semitargeted G116→A mutations as well, although this conclusion is more tentative.

AB - Mutations induced by the (+)-anti-diol epoxide of benzo[a]pyrene [(+)-anti-B[a]PDE] were collected in the supF gene of the Escherichia coli plasmid pUB3. pUB3 was reacted with (+)-anti-B[a]-PDE and then either (1) transformed immediately into E. coli or (2) heated at 80°C for 10 min and then cooled prior to transformation - the latter to probe mechanism [Rodriguez & Loechler (1993) Biochemistry 32, 1759]. Qualitatively, heating did not affect the mutagenic pattern, except at the major base substitution hotspot in supF, G115, where principally G→T mutations were obtained prior to heating, while after heating, G→A and G→C mutations became statistically significantly more prevalent. Several studies have suggested that a heat-induced chemical transformation of a (+)-anti-B[a]PDE adduct at G115 (e.g., into an apurinic site) is not likely to explain the change in mutational pattern. The most likely model is that (+)-anti-B[a]P-N2-Gua is initially trapped in a metastable conformation giving principally G→T mutations, while heating induces a change to a stable conformation(s) resulting in G→T, A, and C mutations. This suggests that adduct conformational complexity is at the root of adduct mutational complexity. To investigate this model, a plasmid (B[a]P-G115-pRE1) with (+)-anti-B[a]P-N2-Gua in the G115 sequence context is constructed using adduct site-specific techniques. Following transformation of B[a]P-G115-pRE1 into E. coli (ES87) cells, targeted G115→T (59%), A (22%), and C (19%) mutations are isolated from (+)-anti-B[a]P-N2-Gua, which approximates the ratio obtained at G115 with (+)-anti-B[a]PDE itself. (+)-anti-B[a]P-N2-Gua principally induced G→T mutations in another sequence context [5′-TGC-3′; Mackay et al. (1992) Carcinogenesis 13, 1415]. Collectively, these findings demonstrate that (+)-anti-B[a]P-N2-Gua is able to induce all three base substitution mutations and that DNA sequence context can influence the qualitative pattern of mutations from (+)-anti-B[a]P-N2-Gua. Finally, it appears that (+)-anti-B[a]P-N2-Gua at G115 may be able to induce semitargeted G116→A mutations as well, although this conclusion is more tentative.

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