Huertas D, Lipps H, Azorin F
a Departament de Biologia Molecular i Cellular Centre d'Investigaciö i Desenvolupament-CSIC , Jordi Girona Salgado 18-26 , 08034 , Barcelona , Spain.
J Biomol Struct Dyn. 1994 Aug;12(1):79-90. doi: 10.1080/07391102.1994.10508089.
Abstract Telomeric DNA sequences are known to adopt unusual DNA structures upon protonation when contained into negatively supercoiled DNA. In this paper, the structural properties of (T(2)AG(3))(n) telomeric sequences of different length is analyzed in detail. Transition to the protonated form is observed at very low pH for (T(2)AG(3))(n<8) sequences. Formation of the protonated form is facilitated by negative supercoiling. The patterns of chemical modification obtained with different chemical reagents indicate that protonation induces denaturation of the (T(2)AG(3))(n) telomeric sequences. Upon denaturation, the "C-rich" strand becomes structured forming, most likely, hairpin-like conformations stabilized by the formation of C(+)·C pairs and, probably, of A(+)·A pairs. The "G-rich" strand of the (T(2)AG(3))(8) sequence shows also signs of becoming structured giving rise to various structural conformers which might include triple- and tetra-stranded conformations. However, in the case of shorter sequences, the "G-rich" strand remains basically single-stranded.
摘要 已知端粒DNA序列在包含于负超螺旋DNA中时，质子化后会呈现出异常的DNA结构。本文详细分析了不同长度的（T(2)AG(3)）(n)端粒序列的结构特性。对于（T(2)AG(3)）(n<8)序列，在极低pH值下观察到向质子化形式的转变。负超螺旋促进了质子化形式的形成。用不同化学试剂获得的化学修饰模式表明，质子化诱导了（T(2)AG(3)）(n)端粒序列的变性。变性后，“富含C的”链形成结构，最有可能形成通过C(+)·C对以及可能的A(+)·A对的形成而稳定的发夹状构象。（T(2)AG(3)）(8)序列的“富含G的”链也显示出形成结构的迹象，产生了各种结构构象，可能包括三链和四链构象。然而，对于较短的序列，“富含G的”链基本上保持单链状态。
