HUMAN TELOMERIC C-STRAND TETRAPLEXES

Citation
S. Ahmed et al., HUMAN TELOMERIC C-STRAND TETRAPLEXES, Nature structural biology, 1(2), 1994, pp. 83-88
Citations number
44
Categorie Soggetti
Biology,"Cytology & Histology
Journal title
ISSN journal
10728368
Volume
1
Issue
2
Year of publication
1994
Pages
83 - 88
Database
ISI
SICI code
1072-8368(1994)1:2<83:HTCT>2.0.ZU;2-2
Abstract
Telomeric C-strand sequences form non-Watson-Crick base-paired structu res in supercoiled plasmids and in oligonucleotides at low pH. Here we examine oligonucleotides composed of 2 or 4 repeats of the human telo meric C-strand sequence d(CCCTAA)(n). At low pH, the 2-repeat molecule forms a dimer which exhibits H1'-H1' nuclear Overhauser effects (NOEs ) between stacked C.C+ base pairs. These NOEs ave characteristic of th e i-motif, which is a tetraplex composed of two intercalated C.C+ dupl exes. The 4-repeat molecule forms an intramolecular monomeric structur e at low pH, suggesting that four contiguous cytosine tracts fold into a C.C+ intercalated tetraplex. These unusual structures may be releva nt to the formation of guanine tetraplexes by complementary G-rich seq uences. They may also provide a general mechanism for self-recognition by nucleic acids.