1u6n

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Solution Structure of an Oligodeoxynucleotide Containing a Butadiene Derived N1 b-Hydroxyalkyl Adduct on Deoxyinosine in the Human N-ras Codon 61 Sequence

Overview

The solution structure of the, N1-(1-hydroxy-3-buten-2(S)-yl)-2'-deoxyinosine adduct arising from the, alkylation of adenine N1 by butadiene epoxide (BDO), followed by, deamination to deoxyinosine, was determined, in the oligodeoxynucleotide, d(CGGACXAGAAG).d(CTTCTCGTCCG). This oligodeoxynucleotide contained the BDO, adduct at the second position of codon 61 of the human N-ras, protooncogene, and was named the ras61 S-N1-BDO-(61,2) adduct. (1)H NMR, revealed a weak C(5) H1' to X(6) H8 NOE, followed by an intense X(6) H8 to, X(6) H1' NOE. Simultaneously, the X(6) H8 to X(6) H3' NOE was weak. The, resonance arising from the T(17) imino proton was not observed. (1)H NOEs, between the butadiene moiety and the DNA positioned the adduct in the, major groove. Structural refinement based upon a total of 364 NOE-derived, distance restraints yielded a structure in which the modified deoxyinosine, was in the high syn conformation about the glycosyl bond, and T(17), the, complementary nucleotide, was stacked into the helix, but not hydrogen, bonded with the adducted inosine. The refined structure provided a, plausible hypothesis as to why this N1 deoxyinosine adduct strongly coded, for the incorporation of dCTP during trans lesion DNA replication, both in, Escherichia coli [Rodriguez, D. A., Kowalczyk, A., Ward, J. B. J., Harris, C. M., Harris, T. M., and Lloyd, R. S. (2001) Environ. Mol. Mutagen. 38, 292-296], and in mammalian cells [Kanuri, M., Nechev, L. N., Tamura, P., J., Harris, C. M., Harris, T. M., and Lloyd, R. S. (2002) Chem. Res., Toxicol. 15, 1572-1580]. Rotation of the N1 deoxyinosine adduct into the, high syn conformation may facilitate incorporation of dCTP via, Hoogsteen-type templating with deoxyinosine, thus generating A-to-G, mutations.

About this Structure

1U6N is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.

Reference

Structure of an oligodeoxynucleotide containing a butadiene oxide-derived N1 beta-hydroxyalkyl deoxyinosine adduct in the human N-ras codon 61 sequence., Scholdberg TA, Merritt WK, Dean SM, Kowalcyzk A, Harris CM, Harris TM, Rizzo CJ, Lloyd RS, Stone MP, Biochemistry. 2005 Mar 8;44(9):3327-37. PMID:15736943

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