1emq
From Proteopedia
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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
1EMQ is a Protein complex structure of sequences from [1]. 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
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