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How long is too long? Effects of loop size on G-quadruplex stability.
Guédin, Aurore; Gros, Julien; Alberti, Patrizia; Mergny, Jean-Louis.
Afiliação
  • Guédin A; INSERM, U869, European Institute of Chemistry and Biology, Bordeaux 2 University, 2 rue Robert Escarpit, Pessac F-33607, France.
Nucleic Acids Res ; 38(21): 7858-68, 2010 Nov.
Article em En | MEDLINE | ID: mdl-20660477
We compared here 80 different sequences containing four tracts of three guanines with loops of variable length (between 1 and 15 bases for unmodified sequences, up to 30 for fluorescently labeled oligonucleotides). All sequences were capable of forming stable quadruplexes, with T(m) above physiological temperature in most cases. Unsurprisingly, the melting temperature was systematically lower in sodium than in potassium but the difference between both ionic conditions varied between 1 and >39°C (average difference: 18.3°C). Depending on the sequence context, and especially for G4 sequences involving two very short loops, the third one may be very long without compromising the stability of the quadruplex. A strong inverse correlation between total loop length and T(m) was found in K(+): each added base leads to a 2°C drop in T(m) or ∼0.3 kcal/mol loss in ΔG°. The trend was less clear in Na(+), with a longer than expected optimal loop length (up to 5 nt). This study will therefore extend the sequence repertoire of quadruplex-prone sequences, arguing for a modification of the widely used consensus (maximal loop size of 7 bases).
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2010 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2010 Tipo de documento: Article