Mutagenesis studies of the major benzo[a]pyrene N2-dG adduct in a 5'-TG versus a 5'-UG sequence: removal of the methyl group causes a modest decrease in the [G->T/G->A] mutational ratio.

The potent mutagen/carcinogen benzo[a]pyrene (B[a]P) is metabolically activated to (+)-anti-B[a]PDE, which induces a full spectrum of mutations primarily at the G:C base pairs (e.g. GC-->TA, GC-->AT, etc.). Each of these mutations can be induced by its major adduct [+ta]-B[a]P-N(2)-dG, where DNA sequence context appears to influence both the quantitative and qualitative pattern of mutagenesis. We noted previously that 5'-TG sequences tend to have a higher fraction of G-->T mutations for both [+ta]-B[a]P-N(2)-dG and (+)-anti-B[a]PDE in comparison with 5'-CG, 5'-GG or 5'-AG sequences. To investigate a possible structural element for this trend, the role (if any) of the methyl group on the 5'-T is considered. Using adduct site-specific means, the [G-->T/G-->A] mutational ratio for [+ta]-B[a]P-N(2)-dG is determined to be approximately 1.08 in a 5'-TGT sequence, and approximately 0.60 in a 5'-UGT sequence. (G-->C mutations are minor.) Although this modest approximately 1.8-fold decrease in [G-->T/G-->A] ratio is statistically significant (P = 0.03), it suggests that the methyl group on the 5'-T is not the main reason why a 5'-T tends to enhance G-->T mutations. This study was prompted by an adduct conformational hypothesis, which predicted that the removal of the methyl group in a 5'-TG sequence would lower the fraction of G-->T mutations; however, the approximately 1.8-fold decrease is too small to do additional experiments to assess whether this conformational hypothesis, or other hypotheses, are the true cause of the decrease, which is discussed in this paper.

[1]  W. Jencks,et al.  Binding energy, specificity, and enzymic catalysis: the circe effect. , 2006, Advances in enzymology and related areas of molecular biology.

[2]  Jun Yin,et al.  A role for DNA polymerase V in G --> T mutations from the major benzo[a]pyrene N2-dG adduct when studied in a 5'-TGT sequence in E. coli. , 2004, DNA repair.

[3]  E. Loechler,et al.  Molecular modeling of the major benzo[a]pyrene N2-dG adduct in cases where mutagenesis results are known in double stranded DNA. , 2003, Mutation research.

[4]  Akinori Sarai,et al.  Free energy calculations for the relative binding affinity between DNA and λ‐repressor , 2003 .

[5]  P. Hainaut,et al.  On the origin of G --> T transversions in lung cancer. , 2003, Mutation research.

[6]  D. Jerina,et al.  A Single Site-specific trans-Opened 7,8,9,10-Tetrahydrobenzo[a]pyrene 7,8-Diol 9,10-EpoxideN 2-Deoxyguanosine Adduct Induces Mutations at Multiple Sites in DNA* 210 , 2003, The Journal of Biological Chemistry.

[7]  S. Amin,et al.  Conformational changes of a benzo[a]pyrene diol epoxide-N(2)-dG adduct induced by a 5'-flanking 5-methyl-substituted cytosine in a (Me)CG double-stranded oligonucleotide sequence context. , 2002, Chemical research in toxicology.

[8]  D. Jerina,et al.  Efficiency and Accuracy of SOS-induced DNA Polymerases Replicating Benzo[a]pyrene-7,8-diol 9,10-Epoxide A and G Adducts* , 2002, The Journal of Biological Chemistry.

[9]  R. Woodgate,et al.  Crystal Structure of a Y-Family DNA Polymerase in Action A Mechanism for Error-Prone and Lesion-Bypass Replication , 2001, Cell.

[10]  R. Fuchs,et al.  The processing of a Benzo(a)pyrene adduct into a frameshift or a base substitution mutation requires a different set of genes in Escherichia coli , 2000, Molecular microbiology.

[11]  E. Loechler,et al.  Factors that influence the mutagenic patterns of DNA adducts from chemical carcinogens. , 2000, Mutation research.

[12]  R. Kozack,et al.  Toward an understanding of the role of DNA adduct conformation in defining mutagenic mechanism based on studies of the major adduct (formed at N(2)-dG) of the potent environmental carcinogen, benzo[a]pyrene. , 2000, Mutation research.

[13]  D. Jerina,et al.  Characterization of the mutational profile of (+)-7R,8S-dihydroxy-9S, 10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene at the hypoxanthine (guanine) phosphoribosyltransferase gene in repair-deficient Chinese hamster V-H1 cells. , 1999, Carcinogenesis.

[14]  D. Weisenberger,et al.  Cytosine Methylation in a CpG Sequence Leads to Enhanced Reactivity with Benzo[a]pyrene Diol Epoxide That Correlates with a Conformational Change* , 1999, The Journal of Biological Chemistry.

[15]  D. Jerina,et al.  The ratio of deoxyadenosine to deoxyguanosine adducts formed by (+)-(7R,8S,9S,10R)-7,8-dihydroxy-9,10-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene in purified calf thymus DNA and DNA in V-79 cells is independent of dose. , 1999, International journal of oncology.

[16]  N. Geacintov,et al.  The major, N2-dG adduct of (+)-anti-B[a]PDE induces G-->A mutations in a 5'-AGA-3' sequence context. , 1999, Carcinogenesis.

[17]  S. Doublié,et al.  Crystal structure of a bacteriophage T7 DNA replication complex at 2.2 Å resolution , 1998, Nature.

[18]  N. Geacintov,et al.  How stereochemistry affects mutagenesis by N2-deoxyguanosine adducts of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene: configuration of the adduct bond is more important than those of the hydroxyl groups. , 1997, Biochemistry.

[19]  N. Geacintov,et al.  The major, N2-dG adduct of (+)-anti-B[a]PDE shows a dramatically different mutagenic specificity (predominantly, G --> A) in a 5'-CGT-3' sequence context. , 1997, Biochemistry.

[20]  D. Patel,et al.  NMR solution structures of stereoisometric covalent polycyclic aromatic carcinogen-DNA adduct: principles, patterns, and diversity. , 1997, Chemical research in toxicology.

[21]  S. Spiegel,et al.  Fidelity of translesional synthesis past benzo[a]pyrene diol epoxide-2'-deoxyguanosine DNA adducts: marked effects of host cell, sequence context, and chirality. , 1996, Biochemistry.

[22]  E. Cavalieri,et al.  Expanded analysis of benzo[a]pyrene-DNA adducts formed in vitro and in mouse skin: their significance in tumor initiation. , 1996, Chemical research in toxicology.

[23]  J. Pelling,et al.  Relating aromatic hydrocarbon-induced DNA adducts and c-H-ras mutations in mouse skin papillomas: the role of apurinic sites. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[24]  N. Geacintov,et al.  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. , 1995, Biochemistry.

[25]  E. Loechler.  How are potent bulky carcinogens able to induce such a diverse array of mutations? , 1995, Molecular carcinogenesis.

[26]  S. Y. Zhang,et al.  Murine squamous cell carcinoma cell lines produced by a complete carcinogenesis protocol with benzo[a]pyrene exhibit characteristic p53 mutations and the absence of H-ras and cyl 1/cyclin D1 abnormalities. , 1994, Carcinogenesis.

[27]  Samuel H. Wilson,et al.  Structures of ternary complexes of rat DNA polymerase beta, a DNA template-primer, and ddCTP. , 1994, Science.

[28]  E. Loechler,et al.  Mutational specificity of the (+)-anti-diol epoxide of benzo[a]pyrene in a supF gene of an Escherichia coli plasmid: DNA sequence context influences hotspots, mutagenic specificity and the extent of SOS enhancement of mutagenesis. , 1993, Carcinogenesis.

[29]  E. Loechler,et al.  Mutagenesis by the (+)-anti-diol epoxide of benzo[a]pyrene: what controls mutagenic specificity? , 1993, Biochemistry.

[30]  M. Benasutti,et al.  Mutagenesis by (+)-anti-B[a]P-N2-Gua, the major adduct of activated benzo[a]pyrene, when studied in an Escherichia coli plasmid using site-directed methods. , 1992, Carcinogenesis.

[31]  B. Glickman,et al.  Induction of specific frameshift and base substitution events by benzo[a]pyrene diol epoxide in excision-repair-deficient Escherichia coli. , 1990, Carcinogenesis.

[32]  J. M. Roman,et al.  DNA adducts from carcinogenic and noncarcinogenic enantiomers of benzo[a]pyrene dihydrodiol epoxide. , 1989, Chemical research in toxicology.

[33]  J. Mccormick,et al.  Kinds of mutations formed when a shuttle vector containing adducts of (+/-)-7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene replicates in human cells. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[34]  Adams Wt,et al.  Statistical test for the comparison of samples from mutational spectra , 1987 .

[35]  B. Duncan.  Isolation of insertion, deletion, and nonsense mutations of the uracil-DNA glycosylase (ung) gene of Escherichia coli K-12 , 1985, Journal of bacteriology.

[36]  A. Dipple.  Polycyclic Aromatic Hydrocarbon Carcinogenesis: An Introduction , 1985 .

[37]  D. Grunberger,et al.  Molecular Biology of Mutagens and Carcinogens , 1983, Springer US.

[38]  D. Phillips.  Fifty years of benzo(a)pyrene , 1983, Nature.

[39]  A. Conney,et al.  Induction of microsomal enzymes by foreign chemicals and carcinogenesis by polycyclic aromatic hydrocarbons: G. H. A. Clowes Memorial Lecture. , 1982, Cancer research.

[40]  B. Weiss,et al.  Specific mutator effects of ung (uracil-DNA glycosylase) mutations in Escherichia coli , 1982, Journal of bacteriology.

[41]  J. Miller,et al.  Carcinogenic epoxides of benzo[a]pyrene and cyclopenta[cd]pyrene induce base substitutions via specific transversions. , 1982, Proceedings of the National Academy of Sciences of the United States of America.

[42]  A. Fersht.  Review Lecture Enzymic editing mechanisms and the genetic code , 1981, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[43]  W. Jencks,et al.  On the attribution and additivity of binding energies. , 1981, Proceedings of the National Academy of Sciences of the United States of America.

[44]  R. Niessner,et al.  polynuclear aromatic hydrocarbons , 2017 .

[45]  R. Kozack,et al.  A hypothesis for what conformation of the major adduct of (+)-anti-B[a]PDE (N2-dG) causes G-->T versus G-->A mutations based upon a correlation between mutagenesis and molecular modeling results. , 1999, Carcinogenesis.

[46]  D. Jerina,et al.  Covalent nucleoside adducts of benzo[a]pyrene 7,8-diol 9,10-epoxides: structural reinvestigation and characterization of a novel adenosine adduct on the ribose moiety , 1991 .

[47]  Jia-Ling Yang,et al.  Kinds and location of mutations induced by (±)-7β,8α- dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene in the coding region of the hypoxanthine (guanine) phosphoribosyltransferase gene in diploid human fibroblasts , 1991 .

[48]  C. Cooper,et al.  Chemical Carcinogenesis and Mutagenesis I , 1990, Handbook of Experimental Pharmacology.

[49]  A. Carothers,et al.  DNA base changes in benzo[a]pyrene diol epoxide-induced dihydrofolate reductase mutants of Chinese hamster ovary cells. , 1990, Carcinogenesis.

[50]  A. Dipple,et al.  Polycyclic aromatic hydrocarbon carcinogens. , 1990, Progress in clinical and biological research.

[51]  P. Grover,et al.  Polycyclic Aromatic Hydrocarbons: Metabolism, Activation and Tumour Initiation , 1990 .

[52]  A. Balmain,et al.  Oncogene activation in chemical carcinogenesis. , 1988, Advances in cancer research.

[53]  Thomas A. Kunkel,et al.  Rapid and efficient site-specific mutagenesis without phenotypic selection. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[54]  P. Grasso.  Carcinogens in Food , 1983 .