Mergny J L, Sun J S, Rougée M, Montenay-Garestier T, Barcelo F, Chomilier J, Hélène C
Laboratoire de Biophysique, INSERM U201, CNRS UA481, Paris, France.
Biochemistry. 1991 Oct 8;30(40):9791-8. doi: 10.1021/bi00104a031.
The specificity of a homopyrimidine oligonucleotide binding to a homopurine-homopyrimidine sequence on double-stranded DNA was investigated by both molecular modeling and thermal dissociation experiments. The presence of a single mismatched triplet at the center of the triplex was shown to destabilize the triple helix, leading to a lower melting temperature and a less favorable energy of interaction. A terminal mismatch was less destabilizing than a central mismatch. The extent of destabilization was shown to be dependent on the nature of the mismatch. Both single base-pair substitution and deletion in the duplex DNA target were investigated. When a homopurine stretch was interrupted by one thymine, guanine was the least destabilizing base on the third strand. However, G in the third strand did not discriminate between a C.G and an A.T base pair. If the stretch of purines was interrupted by a cytosine, the presence of pyrimidines (C or T) in the third strand yielded a less destabilizing effect than purines. This study shows that oligonucleotides forming triple helices can discriminate between duplex DNA sequences that differ by one base pair. It provides a basis for the choice of antigene oligonucleotide sequences targeted to selected sequences on duplex DNA.
通过分子建模和热解离实验研究了同嘧啶寡核苷酸与双链DNA上同嘌呤-同嘧啶序列结合的特异性。三链体中心存在单个错配三联体被证明会使三链螺旋不稳定，导致较低的解链温度和较不利的相互作用能量。末端错配比中心错配的稳定性破坏作用小。稳定性破坏程度取决于错配的性质。研究了双链DNA靶标中的单碱基对替换和缺失。当同嘌呤链被一个胸腺嘧啶打断时，鸟嘌呤是第三链上稳定性破坏作用最小的碱基。然而，第三链上的鸟嘌呤不能区分C.G和A.T碱基对。如果嘌呤链被一个胞嘧啶打断，第三链中嘧啶（C或T）的存在比嘌呤产生的稳定性破坏作用小。这项研究表明，形成三链螺旋的寡核苷酸可以区分相差一个碱基对的双链DNA序列。它为选择靶向双链DNA上选定序列的反基因寡核苷酸序列提供了基础。
