1evm
From Proteopedia
NMR OBSERVATION OF A-TETRAD
Overview
The structure of the telomeric DNA has been a subject of extensive investigation in recent years due to the realization that it has important functional roles to play in vivo and the observations that truncated telomeric sequences exhibit a great variety of 3D structures in aqueous solutions. In this context, we describe here NMR structural studies on two truncated human telomeric DNA sequences, d-AG(3)T and d-TAG(3)T in solutions containing K(+)ions. The G(3)stretches in both the oligonucleotides were seen to form parallel-stranded quadruplexes. However, the AG(3)segment as a whole, had different structural characteristics. The structure of d-AG(3)T revealed the formation of a novel A-tetrad, which was not seen in d-TAG(3)T. The A's in the tetrad had syn glycosidic conformation as opposed to the anti conformation of the G's in the G-tetrads. The A-tetrad stacked well over the adjacent G-tetrad and the twist angle at this step was smaller in d-AG(3)T than in d-TAG(3)T. These observations are expected to be significant from the point of view of structural diversity and recognition in telomeres.
About this Structure
Full crystallographic information is available from OCA.
Reference
NMR studies on truncated sequences of human telomeric DNA: observation of a novel A-tetrad., Patel PK, Koti AS, Hosur RV, Nucleic Acids Res. 1999 Oct 1;27(19):3836-43. PMID:10481022 Page seeded by OCA on Fri May 2 15:34:13 2008
