与果蝇卫星重复序列形成三链螺旋。铜离子意外的稳定作用。

Triple helix formation with Drosophila satellite repeats. Unexpected stabilization by copper ions.

作者信息

Horn Virginie, Lacroix Laurent, Gautier Thierry, Takasugi Masashi, Mergny Jean-Louis, Lacoste Jérôme

机构信息

Laboratoire de Biologie Moléculaire et Cellulaire de la Différenciation, INSERM UR 309, Institut Albert Bonniot, Rond-point de la Chantourne, 38700 Grenoble, France.

出版信息

Biochemistry. 2004 Sep 7;43(35):11196-205. doi: 10.1021/bi049287t.

DOI:10.1021/bi049287t

PMID:15366929

Abstract

The Drosophila melanogaster (AAGAGAG)(n) satellite repeat represents up to 1.5% of the entire fly genome and may adopt non-B DNA structures such as pyrimidine triple helices. UV melting and electrophoretic mobility shift assay experiments were used to monitor the stability of intermolecular triple helices as a function of size, pH, and backbone or base modification. Three to four repeats of the heptanucleotide motif were sufficient to allow the formation of a stable complex, especially when modified TFOs were used. Unexpectedly, low concentrations (40-100 microM) of Cu(2+) were found to favor strongly pyrimidine triplex formation under near-physiological conditions. In contrast, a much higher magnesium concentration was required to stabilize these triplexes significantly, suggesting that copper may be an essential stabilizing factor for pyrimidine triplexes.

摘要

黑腹果蝇的(AAGAGAG)(n)卫星重复序列占果蝇整个基因组的比例高达1.5%，并且可能呈现非B型DNA结构，如嘧啶三链螺旋。采用紫外熔解和电泳迁移率变动分析实验来监测分子间三链螺旋的稳定性，该稳定性是大小、pH值以及主链或碱基修饰的函数。七核苷酸基序的三到四个重复序列足以形成稳定的复合物，尤其是当使用经过修饰的三链形成寡核苷酸（TFO）时。出乎意料的是，发现在近生理条件下，低浓度（40 - 100微摩尔）的铜离子（Cu(2+)）强烈促进嘧啶三链体的形成。相比之下，需要高得多的镁离子浓度才能显著稳定这些三链体，这表明铜可能是嘧啶三链体的一种重要稳定因子。