Characterization of Lysine-Guanine Cross-Links upon One-Electron Oxidation of a Guanine-Containing Oligonucleotide in the Presence of a Trilysine Peptide

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• 作者：Sandrine Perrier ; Jö ; rg Hau ; Didier Gasparutto ; Jean Cadet ; Alain Favier ; and Jean-Luc Ravanat
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：May 3, 2006
• 年：2006
• 卷：128
• 期：17
• 页码：5703 - 5710
• 全文大小：113K
• 年卷期：v.128,no.17(May 3, 2006)
• ISSN：1520-5126

文摘

Formation of DNA-protein cross-links involving the initial formation of a guanine radical cationwas investigated. For this purpose, riboflavin-mediated photosensitization of a TGT oligonucleotide in aeratedaqueous solution in the presence of the KKK tripeptide was performed. We have shown that the nucleophilicaddition of the -amino group of the central lysine residue of KKK to the C8 atom of either the guanineradical cation or its deprotonated form gives rise to the efficient formation of a N-(guanin-8-yl)-lysine cross-link. Interestingly, the time course of formation of the above-mentioned cross-link was found to be notlinear with the time of irradiation, and its formation rapidly reached a plateau. This is explained by secondarydecomposition of the initially generated cross-link which could be further oxidized more efficiently thanstarting TGT oligonucleotide. One-electron oxidation of the initially generated cross-link was found to producemainly two diastereomeric cross-links exhibiting a spiroimino-trilysine-dihydantoin structure as inferred fromenzymatic digestion, CD, UV, NMR and mass spectrometry measurements. In addition, other minor cross-links, for which formation was favored at acidic pH, were assigned as lysine-guanine adducts in which themodified guanine base exhibits a guanidino-trilysine-iminohydantoin structure. A proposed mechanism forthe formation of the different detected oligonucleotide-peptide cross-links is given. The high yield offormation of the detected cross-links strongly suggests that a DNA-protein cross-link involving a lysineresidue linked to the C8 position of guanine could be generated in cellular systems if a lysine is located inthe close vicinity of a guanine radical cation. KEYWORDS: oxidatively generated DNA damage,photosensitization, guanine radical cation, DNA-protein cross-links.