Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Structure of a C-rich strand fragment of the human centromeric satellite III: A pH-dependent intercalation topology
Autore:
Nonin-Lecomte, S; Leroy, JL;
Indirizzi:
Ecole Polytech, PMC Grp Biophys, F-91128 Palaiseau, France Ecole PolytechPalaiseau France F-91128 ophys, F-91128 Palaiseau, France CNRS, UMR 7643, F-91128 Palaiseau, France CNRS Palaiseau France F-91128CNRS, UMR 7643, F-91128 Palaiseau, France
Titolo Testata:
JOURNAL OF MOLECULAR BIOLOGY
fascicolo: 2, volume: 309, anno: 2001,
pagine: 491 - 506
SICI:
0022-2836(20010601)309:2<491:SOACSF>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
NMR COUPLING-CONSTANTS; PAIR OPENING KINETICS; I-MOTIF; CRYSTAL-STRUCTURE; NUCLEIC-ACIDS; BASE-PAIRS; PROTON-EXCHANGE; HUMAN TELOMERE; DNA FRAGMENTS; SPECTROSCOPY;
Keywords:
i-motif; centromere; satellite III; intercalation; NMR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
59
Recensione:
Indirizzi per estratti:
Indirizzo: Nonin-Lecomte, S Ecole Polytech, PMC Grp Biophys, F-91128 Palaiseau, France Ecole Polytech Palaiseau France F-91128 laiseau, France
Citazione:
S. Nonin-Lecomte e J.L. Leroy, "Structure of a C-rich strand fragment of the human centromeric satellite III: A pH-dependent intercalation topology", J MOL BIOL, 309(2), 2001, pp. 491-506

Abstract

Repetitive DNA sequences may adopt unusual pairing arrangements. At acid to neutral pH, cytidine-rich DNA oligodeoxynucleotides can form the i-motif structure in which two parallel-stranded duplexes with C Ct pairs are intercalated head-to-tail. The i-motif may be formed by multimeric associations or by intra-molecular folding, depending on the number of cytidine tracts, the nucleotide sequences between them, and the experimental conditions. We have found that a natural fragment of the human centromeric sat ellite III, d(CCATTCCATTCCTTTCC), can form two monomeric i-motif structures that differ in their intercalation topology and that are favored at pH values higher (the eta -form) and lower (the lambda -form) than 4.6. The change in intercalation may be related to adenine protonation in the loops. We studied the uridine derivative methylated on the first cytidine base, d(5mCCATTCCAUTCCUTTCC), whose proton spectrum is better resolved. The intercalation topologies are (C7.C17)/(5mC1.C11)/(C6.C16)/(C2.C12) for form lambda and (5mC1.C11)/(C7.C17)/(C2.C12)/ (C6.C16) for form eta. We have solved the structure of the eta -form, and we present a model for the h-form. The switch from eta to lambda involves disruption of the i-motif. In both forms,the central AUT linker crosses the wide groove, and the first and the third linkers loop across the minor grooves. The i-motif core is extended in the eta -form by the inter-loop reverse Watson-Crick A3.U13 pair, whose dissociation constant is around 10(-2) at 0 degreesC, and in the lambda -form bythe interloop T5.T15 pair. In contrast, d(5mCCATTCCTTACCTTTCC) folds into a pH-independent structure that has the same intercalation topology as the h-form. The i-motif core isextended below by the interloop T5.T15 pair and closed on top by the T8.A10 pair. In contrast, d(5mCCATTCCTTACCTTTCC) folds into a pH-independent structure that has the same intercalation topology as the h-form. The i-motif core isextended below by the interloop T5.T15 pair and closed on top by the T8.A10 pair. Thus, the C-rich strand of the human satellite III tandem repeats, like the G-rich strand, can fold into various compact structures. The relevance ofthese features to centromeric function remains unknown. (C) 2001 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/09/20 alle ore 19:15:12