Download MendeleyGiardia Telomeric Sequence d(TAGGG)(4) Forms Two Intramolecular G-Quadruplexes in K(+) Solution: Effect of Loop Length and Sequence on the Folding Topology.
Hu, L., Lim, K.W., Bouaziz, S., Phan, A.T.(2009) J Am Chem Soc 131: 16824-16831
- PubMed: 19874015
- DOI: https://doi.org/10.1021/ja905611c
- Primary Citation of Related Structures:
2KOW - PubMed Abstract:
Recently, it has been shown that in K(+) solution the human telomeric sequence d[TAGGG(TTAGGG)(3)] forms a (3 + 1) intramolecular G-quadruplex, while the Bombyx mori telomeric sequence d[TAGG(TTAGG)(3)], which differs from the human counterpart only by one G deletion in each repeat, forms a chair-type intramolecular G-quadruplex, indicating an effect of G-tract length on the folding topology of G-quadruplexes. To explore the effect of loop length and sequence on the folding topology of G-quadruplexes, here we examine the structure of the four-repeat Giardia telomeric sequence d[TAGGG(TAGGG)(3)], which differs from the human counterpart only by one T deletion within the non-G linker in each repeat. We show by NMR that this sequence forms two different intramolecular G-quadruplexes in K(+) solution. The first one is a novel basket-type antiparallel-stranded G-quadruplex containing two G-tetrads, a G x (A-G) triad, and two A x T base pairs; the three loops are consecutively edgewise-diagonal-edgewise. The second one is a propeller-type parallel-stranded G-quadruplex involving three G-tetrads; the three loops are all double-chain-reversal. Recurrence of several structural elements in the observed structures suggests a "cut and paste" principle for the design and prediction of G-quadruplex topologies, for which different elements could be extracted from one G-quadruplex and inserted into another.
Organizational Affiliation:
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371.
