A novel chair-type G-quadruplex formed by a Bombyx mori telomeric sequence.
Recently, the human telomeric d[TAGGG(TTAGGG)(3)] sequence has been shown to form in K(+) solution an intramolecular (3+1) G-quadruplex structure, whose G-tetrad core contains three strands oriented in one direction and the fourth in the opposite direction. Here we present a study on the structure of the Bombyx mori telomeric d[TAGG(TTAGG)(3)] sequence, which differs from the human counterpart only by one G deletion in each repeat. We found that this sequence adopted multiple G-quadruplex structures in K(+) solution. We have favored a major G-quadruplex form by a judicious U-for-T substitution in the sequence and determined the folding topology of this form. We showed by NMR that this was a new chair-type intramolecular G-quadruplex which involved a two-layer antiparallel G-tetrad core and three edgewise loops. Our result highlights the effect of G-tract length on the folding topology of G-quadruplexes, but also poses the question of whether a similar chair-type G-quadruplex fold exists in the human telomeric sequences.
Amrane
Samir
S
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371.
Ang
Rita Wan Lin
RW
Tan
Zhong Ming
ZM
Li
Chun
C
Lim
Joefina Kim Cheow
JK
Lim
Jocelyn Mei Wen
JM
Lim
Kah Wai
KW
Phan
Anh Tuân
AT
D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics*; D002942:Circular Dichroism; D054856:G-Quadruplexes; D008958:Models, Molecular; D009038:Motion; D019906:Nuclear Magnetic Resonance, Biomolecular; D013056:Spectrophotometry, Ultraviolet; D016615:Telomere / Q000737:chemistry*