Taniguchi Yosuke, Kool Eric T
Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
Nucleic Acids Symp Ser (Oxf). 2007(51):217-8. doi: 10.1093/nass/nrm109.
A number of mutations that arise in the cell come from oxidative damage to DNA bases. Oxidation of purine bases at the 8-position, yielding 8-oxoguanosine and 8-oxoadenosine, results in conformation changes that cause miscoding during DNA replication. For example, 8-oxodG in the syn conformation is complementary to adenine in the hydrogen bonding. Here, we report the synthesis, biophysical and biochemical properties of low-polarity shape mimics of 8-oxopurines. A 2-chloro-4-fluoroindole (1) nucleoside was designed as a mimic of 8-oxodG, and a 2-chloro-4-methylbenzimidazole nucleoside (2) as a mimic of 8-oxodA. Structural studies of the free nucleoside revealed that both bases are preferred syn conformation, thus mimicking the conformation of the oxopurine nucleosides. Base pairing studies showed that both compounds in the oligonucleotides pair with selectivity for purine partners. In the DNA template containing new oxopurine analogs, dATP and dGTP were incorporated opposite 1 and 2 respectively by the Klenow. Moreover, 5'-triphosphate derivatives (3 and 4) were incorporated into DNA opposite purine nucleobase. Thus the new analogs are expected to be useful as mechanistic probes cellular responses to DNA oxidative damage.
细胞中出现的许多突变源于DNA碱基的氧化损伤。嘌呤碱基在8位发生氧化，产生8-氧代鸟苷和8-氧代腺苷，导致构象改变，从而在DNA复制过程中引起错配编码。例如，处于顺式构象的8-氧代鸟嘌呤在氢键作用下与腺嘌呤互补。在此，我们报告了8-氧代嘌呤低极性形状模拟物的合成、生物物理和生化特性。设计了一种2-氯-4-氟吲哚（1）核苷作为8-氧代鸟嘌呤的模拟物，以及一种2-氯-4-甲基苯并咪唑核苷（2）作为8-氧代腺苷的模拟物。对游离核苷的结构研究表明，两种碱基都优先处于顺式构象，从而模拟了氧代嘌呤核苷的构象。碱基配对研究表明，寡核苷酸中的两种化合物都对嘌呤配对伙伴具有选择性配对。在含有新的氧代嘌呤类似物的DNA模板中，Klenow酶分别将dATP和dGTP掺入与1和2相对的位置。此外，5'-三磷酸衍生物（3和4）被掺入与嘌呤核碱基相对的DNA中。因此，这些新的类似物有望作为研究细胞对DNA氧化损伤反应机制的探针。
