Hiratou T, Tsukahara S, Takai K, Koyanagi Y, Yamamoto N, Takaku H
Department of Industrial Chemistry, Chiba Institute of Technology, Japan.
Nucleic Acids Symp Ser. 1997(37):221-2.
Replication of retroviral RNA into double-stranded DNA is catalyzed by reverse transcriptase (RT). The polypurine tract (PPT) serves as a primer for plus-strand DNA synthesis and is highly conserved among HIV-1. The PPT region is a possible target for triple-helix formation. Here, we show the effects of triple-helix formation by analyses of melting temperature and gel shift using a foldback triplex-forming-oligonucleotides (FTFOs). We found that the FTFOs containing phosphorothioate groups at the 3'- and 5'-ends, or inside the hairpin loop, exhibited greater exonuclease resistance than the unmodified FTFOs. Several triplex oligonucleotides have thermal stability. The abilities of the FTFOs (DsDG-37) containing the guanosine in place of the cytidine in the third Hoogsteen base-pairing strand to inhibit HIV-1 replications were examined. The FTFOs (DsDG-37) inhibit the replication of HIV-1 more efficiently than the FTFOs (DsD-37) indicating sequence-specific inhibition of HIV-1 replication.
逆转录酶（RT）催化逆转录病毒RNA复制成双链DNA。多聚嘌呤序列（PPT）作为正链DNA合成的引物，在HIV-1中高度保守。PPT区域是形成三链螺旋的可能靶点。在此，我们通过使用回折三链体形成寡核苷酸（FTFO）分析解链温度和凝胶迁移来展示三链螺旋形成的影响。我们发现，在3'端和5'端或发夹环内部含有硫代磷酸酯基团的FTFO比未修饰的FTFO表现出更强的核酸外切酶抗性。几种三链体寡核苷酸具有热稳定性。研究了在第三条Hoogsteen碱基配对链中用鸟苷取代胞苷的FTFO（DsDG-37）抑制HIV-1复制的能力。FTFO（DsDG-37）比FTFO（DsD-37）更有效地抑制HIV-1复制，表明对HIV-1复制具有序列特异性抑制作用。
