1emq
From Proteopedia
NMR OBSERVATION OF T-TETRADS IN A PARALLEL STRANDED DNA QUADRUPLEX FORMED BY SACCHAROMYCES CEREVISIAE TELOMERE REPEATS
Overview
We report here the NMR structure of the DNA sequence d-TGGTGGC containing two repeats of Saccharomyces cerevisiae telomere DNA which is unique in that it has a single thymine in the repeat sequence and the number of Gs can vary from one to three. The structure is a novel quadruplex incor-porating T-tetrads formed by symmetrical pairing of four Ts via O4-H3 H-bonds in a plane. This is in contrast to the previous results on other telomeric sequences which contained more than one T in the repeat sequences and they were seen mostly in the flexible regions of the structures. We observed that the T4-tetrad was nicely accommodated in the center of the G-quadruplex, but it caused a small underwinding of the right handed helix. The T tetrad stacked well on the adjacent G3-tetrad, but poorly on the G5 tetrad. Likewise, T1 also formed a stable T-tetrad at the 5' end of the quadruplex. To our knowledge, this is the first report of T-tetrad formation in DNA structures. These observations are of significance from the points of view of both structural diversity and specific recognitions.
About this Structure
Full crystallographic information is available from OCA.
Reference
NMR observation of T-tetrads in a parallel stranded DNA quadruplex formed by Saccharomyces cerevisiae telomere repeats., Patel PK, Hosur RV, Nucleic Acids Res. 1999 Jun 15;27(12):2457-64. PMID:10352174 Page seeded by OCA on Fri May 2 15:17:14 2008
