title: Efficient Thymidine-Selective DNA Interstrand Photo-activated Crosslinking by the 6-Thioguanine Connected via an Ethylene-Linker to the 2'-Deoxyribose Unit.
abstract: Cross-linking is a widely-used technology in the studies of DNA, RNA and their complexes with proteins. Intrinsically active alkylating moieties and photo-activated agents are chemically or enzymatically incorporated into nucleic acids. Thionucleobases resemble the corresponding natural bases, and form cross-links by UVA irradiation. They form cross-links only with a site in close contact, thereby allowing identification of the contacts within the nucleic acids and/or between the nucleic acids and proteins in complex nucleoprotein assemblies. On the other hand, the thionucleobase forms a cross-link less efficiently for the reaction with the opposite natural base in the DNA duplex. In this study, 6-thioguanine was connected to 2'-deoxyribose through an ethylene linker at the 1'-position (Et-thioG). The linker was expected to bring the 6-thio group close to the nucleobase in the opposite strand. In a duplex in which the 2'-deoxy-6-thioguanosine (6-thio-dG) did not form a crosslink, Et-thioG efficiently formed crosslink with a high selectivity for T by UVA irradiation, but with a much lower efficiency for dA, dG, dC, 5-methyl-dC or dU. Interestingly, the yield of the photo-crosslinked product with dT was effectively improved in the presence of dithiothreitol or sodium hydrosulfide (NaSH) at a low UVA irradiation dose. The efficient and selective cross-link formation at a low UVA dose may be beneficial for the biological application of Et-thioG.
authors: Graduate School of Pharmaceutical Sciences, Kyushu University.
authors: Takamasa
authors: T
authors: Nishioka
authors: Ikuya
authors: I
authors: Oshiro
authors: Kazumitsu
authors: K
authors: Onizuka
authors: Yosuke
authors: Y
authors: Taniguchi
authors: Shigeki
authors: S
authors: Sasaki
mesh_terms: D003432:Cross-Linking Reagents / Q000138:chemical synthesis / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D003855:Deoxyribose / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D055668:Photochemical Processes; D013866:Thioguanine / Q000737:chemistry*; D013936:Thymidine / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D005030:Ethylenes; D003855:Deoxyribose; D004247:DNA; C036216:ethylene; D013866:Thioguanine; D013936:Thymidine