Orientation of the Crotonaldehyde-Derived N2-[3-Oxo-1(S)-methyl-propyl]-dG DNA Adduct Hinders Interstrand Cross-Link Formation in the 5'-CpG-3' Sequence

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• 作者：Young-Jin Cho ; Hao Wang ; Ivan D. Kozekov ; Albena Kozekova ; Andrew J. Kurtz ; Jaison Jacob ; Markus Voehler ; Jarrod Smith ; Thomas M. Harris ; Carmelo J. Rizzo ; R. Stephen Lloyd ; Michael P. Stone
• 刊名：Chemical Research in Toxicology
• 出版年：2006
• 出版时间：August 2006
• 年：2006
• 卷：19
• 期：8
• 页码：1019 - 1029
• 全文大小：746K
• 年卷期：v.19,no.8(August 2006)
• ISSN：1520-5010

文摘

The conformation of the crotonaldehyde-derived N²-[3-oxo-1(S)-methyl-propyl]-dG adduct in theoligodeoxynucleotide 5'-d(G¹C²T³A⁴G⁵C⁶X⁷A⁸G⁹T¹⁰C¹¹C¹²)-3'·5'-d(G¹³G¹⁴A¹⁵C¹⁶T¹⁷C¹⁸G¹⁹C²⁰T²¹A²²G²³C²⁴)-3', where X = N²-[3-oxo-1(S)-methyl-propyl]-dG, is reported. This adduct arises from opening of thecyclic N²-(S--CH₃--OH-1,N²-propano-2')-dG adduct when placed opposite dC in duplex DNA. Thisoligodeoxynucleotide contains the 5'-CpG-3' sequence in which the N²-(R--CH₃--OH-1,N²-propano-2')-dG but not the N²-(S--CH₃--OH-1,N²-propano-2')-dG adduct preferentially formed an interstrandcarbinolamine cross-link [Kozekov, I. D., Nechev, L. V., Moseley, M. S., Harris, C. M., Rizzo, C. J.,Stone, M. P., and Harris, T. M. (2003) J. Am. Chem. Soc. 125, 50-61; Cho, Y.-J., Wang, H., Kozekov,I. D., Kurtz, A. J., Jacob, J., Voehler, M., Smith, J., Harris, T. M., Lloyd, R. S., Rizzo, C. J., and Stone,M. P. (2006) Chem. Res. Toxicol. 19, 195-208]. Analysis of ¹H NOE data, chemical shift perturbations,and deoxyribose pseudorotations and backbone torsion angles suggested the presence of a stable andordered DNA conformation at pH 9.3 and 30 C, with minimal conformational perturbation. The spectralline widths of the adduct protons were comparable to those of the oligodeoxynucleotide, suggesting thatthe correlation times of these protons were similar to those of the overall duplex. The crotonaldehydic-derived methyl protons showed NOEs in the 5'-direction to C¹⁸ H1', G¹⁹ H1', and G¹⁹ H4' in thecomplementary strand of the duplex. The aldehyde proton of the adduct exhibited NOEs in the 3'-directionto A⁸ H1' and A⁸ H4' in the modified strand. All of these NOEs involved DNA protons facing the minorgroove. Molecular dynamics calculations, restrained by distances and torsion angles derived from theNMR data, revealed that within the minor groove, the aldehyde of the N²-[3-oxo-1(S)-methyl-propyl]-dG adduct oriented in the 3'-direction, while the 1(S) methyl group oriented in the 5'-direction. Thispositioned the aldehyde distal to the G¹⁹ exocyclic amine and provided a rationale as to why the N²-(S--CH₃--OH-1,N²-propano-2')-dG adduct generated interstrand cross-links less efficiently than did theN²-(R--CH₃--OH-1,N²-propano-2')-dG adduct.