HUMAN TELOMERIC C-STRAND TETRAPLEXES
HUMAN TELOMERIC C-STRAND TETRAPLEXES
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DOI：
10.1038/nsb0294-83
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发表时间：
1994-02-01
期刊：
影响因子：
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通讯作者：
HENDERSON, E
中科院分区：
文献类型：
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作者：
AHMED, S;KINTANAR, A;HENDERSON, E
端粒C链序列在超螺旋质粒和低pH值的寡核苷酸中形成非沃森-克里克碱基配对结构。在这里，我们研究了由2或4个重复的人类端粒C链序列d（CCCTAA）（n）组成的寡核苷酸。在低pH下，2-重复分子形成二聚体，其在堆叠的C.C+碱基对之间表现出H1 '-H1'核奥弗豪泽效应（NOE）。这些NOE具有i基序的特征，i基序是由两个插入的C.C+双链体组成的四链体。4-重复分子在低pH下形成分子内单体结构，表明四个连续的胞嘧啶束折叠成C.C+插入的四链体。这些不寻常的结构可能与互补的富含G的序列形成鸟嘌呤四链体有关。它们还可以提供核酸自我识别的一般机制。
Telomeric C-strand sequences form non-Watson-Crick base-paired structures in supercoiled plasmids and in oligonucleotides at low pH. Here we examine oligonucleotides composed of 2 or 4 repeats of the human telomeric C-strand sequence d(CCCTAA)(n). At low pH, the 2-repeat molecule forms a dimer which exhibits H1'-H1' nuclear Overhauser effects (NOEs) between stacked C.C+ base pairs. These NOEs ave characteristic of the i-motif, which is a tetraplex composed of two intercalated C.C+ duplexes. The 4-repeat molecule forms an intramolecular monomeric structure at low pH, suggesting that four contiguous cytosine tracts fold into a C.C+ intercalated tetraplex. These unusual structures may be relevant to the formation of guanine tetraplexes by complementary G-rich sequences. They may also provide a general mechanism for self-recognition by nucleic acids.