1xue
From Proteopedia
|
STRUCTURE OF GTGGAATGCAATGGAAC HAIRPIN, NMR, 10 STRUCTURES
Overview
Recently, we established that satellite III (TGGAA)n tandem repeats, which, occur at the centromeres of human chromosomes, pair with themselves to, form an unusual "self-complementary" antiparallel duplex containing (GGA)2, motifs in which two unpaired guanines from opposite strands intercalate, between sheared G.A base pairs. In separate studies, we have also, established that the GCA triplet does not form bimolecular (GCA)2 motifs, but instead promotes the formation of hairpins containing a GCA-turn motif, in which the loop contains a single cytidine closed by a sheared G.A pair., Since TGCAA is the most frequent variant of TGGAA found in satellite III, repeats, we reasoned that the potential of this variant to form GCA-turn, miniloop fold-back structures might be an important factor in modulating, the local structure in natural (TGGAA)n repeats. We report here the, NMR-derived solution structure of the heptadecadeoxynucleotide, (G)TGGAATGCAATGGAA(C) in which a central TGCAA pentamer is flanked by two, TGGAA pentamers. This 17-mer forms a rather unusual and very stable, hairpin structure containing eight base pairs in the stem, only four of, which are Watson-Crick pairs, and a loop consisting of a single cytidine, residue. The stem contains a (GGA)2 motif with intercalative 14G/4G, stacking between two sheared G.A base pairs; the loop end of the stem, consists of a sheared 8G.10A closing pair with the cytosine base of the 9C, loop stacked on 8G. The remarkable stability of this unusual hairpin, structure (Tm = 63 degrees C) suggests that it probably plays an important, role in modulating the folding of satellite III (TGGAA)n repeats at the, centromere.
About this Structure
1XUE is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
A single G-to-C change causes human centromere TGGAA repeats to fold back into hairpins., Zhu L, Chou SH, Reid BR, Proc Natl Acad Sci U S A. 1996 Oct 29;93(22):12159-64. PMID:8901550
Page seeded by OCA on Sun Nov 25 02:56:12 2007
