Mechanism of intermolecular purine-purine-pyrimidine triple helix stabilization by comb-type polylysine graft copolymer at physiologic potassium concentration.
Mechanism of intermolecular purine-purine-pyrimidine triple helix stabilization by comb-type polylysine graft copolymer at physiologic potassium concentration.
复制标题
生理钾浓度下梳型聚赖氨酸接枝共聚物稳定分子间嘌呤-嘌呤-嘧啶三螺旋的机制。
DOI：
10.1021/bc990166t
复制
发表时间：
2000
影响因子：
4.7
通讯作者：
A. Maruyama
中科院分区：
文献类型：
--
作者：
A. Ferdous;T. Akaike;A. Maruyama
我们之前报道了一种新的策略，通过梳型聚(L-赖氨酸)-接枝-葡聚糖共聚物在生理上相关的pH、温度和钾(K(+))浓度下稳定哺乳动物基因启动子中的嘌呤基序三链DNA[Ferdous等人，(1998年)核酸研究报告26,3949-3954]。在这里，我们描述了共聚物在生理K(+)浓度下稳定嘌呤基序三链DNA的主要贡献(S)。在K(+)介导的抑制嘌呤基序三链形成的研究中，很早就有人提出通过鸟嘌呤四元组形成富含鸟嘌呤的三链形成寡核苷酸(TFOS)的自聚集。然而，在我们的反应条件下观察到的K(+)的严重抑制作用并非如此。富含G的TFO形成三链的速率显著降低是抑制K(+)的主要因素。有趣的是，在共聚物的存在下，三链的形成速度大大增加，并且没有观察到K(+)诱导的预制三链的解离。此外，该共聚物的三链促进/稳定效率惊人地高于生理浓度的精胺。因此，在体外生理条件下，TFO与靶双链结合常数的绝对增加可能是共聚物介导的三链稳定的主要机制来源。
We previously reported a novel strategy to stabilize purine motif triplex DNA within a mammalian gene promoter at physiologically relevant pH, temperature, and potassium (K(+)) concentrations by a comb-type poly(L-lysine)-graft-dextran copolymer [Ferdous et al., (1998) Nucleic Acids Res. 26, 3949-3954]. Here we describe the major contribution(s) of the copolymer to stabilize the purine motif triplex DNA at physiological K(+) concentrations. Self-aggregation through guanine-quartet formation of guanine-rich (G-rich) triplex-forming oligonucleotides (TFOs) has long been proposed for K(+)-mediated inhibition of the purine motif triplex formation. However, this was not the case for the severe inhibitory effect of K(+) observed under our reaction conditions. Rather significant decrease in rate of triplex formation involving a G-rich TFO was a major factor to confer K(+) inhibition. Interestingly, in the presence of the copolymer the rate of triplex formation was tremendously increased and K(+)-induced dissociation of preformed triplexes was not observed. Moreover, the triplex-promoting/stabilizing efficiency of the copolymer was amazingly higher than that of physiological concentrations of spermine. An absolute increase in binding constant of the TFO to the target duplex could therefore be the predominant mechanistic source for the copolymer-mediated triplex stabilization under physiological conditions in vitro.