聚（dA）·聚（dT）在较高温度下形成非常稳定的核小体。

Poly(dA).poly(dT) forms very stable nucleosomes at higher temperatures.

作者信息

Puhl H L, Behe M J

机构信息

Department of Chemistry, Lehigh University, Bethlehem, PA 18015.

出版信息

J Mol Biol. 1995 Feb 3;245(5):559-67. doi: 10.1006/jmbi.1994.0046.

DOI:10.1006/jmbi.1994.0046

PMID:7844826

Abstract

The synthetic polymer poly(dA).poly(dT) was long thought to be refractory to nucleosome formation. Several years ago our laboratory demonstrated that the polymer could be mixed with authentic nucleosomes in a low-salt exchange procedure to form a nucleoprotein complex that behaved in a manner identical with that of nucleosomes. Competitive exchange assays at 37 degrees C showed that the homopolymer reconstituted about as well as heterogenous-sequence DNA. However, studies by other laboratories have shown that the conformation of poly(dA).poly(dT) depends on temperature; the polymer converts from its well-known, atypical structure, found at ambient temperature, to a conformation more closely resembling a canonical B form as temperature is increased. We have measured the ability of the homopurine.homopyrimidine to form nucleosomes as a function of temperature. It is seen that poly(dA).poly(dT) forms nucleosomes more strongly as the temperature of the exchange mixture is increased, so that poly(dA).(dT) outcompetes heterogeneous-sequence DNA for histones at elevated temperatures.

摘要

合成聚合物聚（dA）·聚（dT）长期以来被认为难以形成核小体。几年前，我们实验室证明，在低盐交换过程中，该聚合物可与真实的核小体混合，形成一种核蛋白复合物，其行为方式与核小体相同。37℃下的竞争性交换试验表明，这种同聚物的重构效果与异源序列DNA相当。然而，其他实验室的研究表明，聚（dA）·聚（dT）的构象取决于温度；随着温度升高，该聚合物从其在环境温度下常见的非典型结构转变为更接近标准B型的构象。我们已测量了这种同嘌呤·同嘧啶聚合物形成核小体的能力随温度的变化情况。可以看到，随着交换混合物温度升高，聚（dA）·聚（dT）形成核小体的能力增强，以至于在高温下，聚（dA）·聚（dT）比异源序列DNA更能竞争组蛋白。