Structural studies have shown that four G-tracts along a DNA strand are the minimal requirement for intramolecular G-quadruplex formation. Longer DNA sequences containing multiple of four G-tracts could, in principle, form higher-order structures based on multiple G-quadruplex blocks. This later condition is abundantly verified for the telomeric single-stranded overhang (~ 200 nt) constituted of tens of TTAGGG repeats, thus opening new interesting questions about the structure of the “real” telomeric DNA. How many quadruplex units form in the human telomeric overhang ? Which type of quadruplex topologies ? Do they interact or not ? What about their binding properties ? Although, many of these questions are still unanswered, they recently began to be object of experimental and computational studies. The question about the existence and relevance of these higher-order quadruplex structures in the human genome is now an interesting and stimulating research topic in the quadruplex field. The recent results, the unsolved problems and the future prospective on the intramolecular telomeric higher-order quadruplex structures are the main topic of this review. Other studies on long telomeric RNA sequences and on other intramolecular (non telomeric) DNA higher order quadruplex structures are also presented.
Higher-order Quadruplex Structures / Petraccone, Luigi. - 330:(2013), pp. 23-46. [10.1007/128-2012-350]
Higher-order Quadruplex Structures
PETRACCONE, LUIGI
2013
Abstract
Structural studies have shown that four G-tracts along a DNA strand are the minimal requirement for intramolecular G-quadruplex formation. Longer DNA sequences containing multiple of four G-tracts could, in principle, form higher-order structures based on multiple G-quadruplex blocks. This later condition is abundantly verified for the telomeric single-stranded overhang (~ 200 nt) constituted of tens of TTAGGG repeats, thus opening new interesting questions about the structure of the “real” telomeric DNA. How many quadruplex units form in the human telomeric overhang ? Which type of quadruplex topologies ? Do they interact or not ? What about their binding properties ? Although, many of these questions are still unanswered, they recently began to be object of experimental and computational studies. The question about the existence and relevance of these higher-order quadruplex structures in the human genome is now an interesting and stimulating research topic in the quadruplex field. The recent results, the unsolved problems and the future prospective on the intramolecular telomeric higher-order quadruplex structures are the main topic of this review. Other studies on long telomeric RNA sequences and on other intramolecular (non telomeric) DNA higher order quadruplex structures are also presented.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.