Sá-Carvalho D, Traub-Cseko Y M
Laboratório de Biologia Molecular de Tripanosomatídeos, DBBM, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
Mol Biochem Parasitol. 1995 Jun;72(1-2):103-9. doi: 10.1016/0166-6851(95)00089-j.
Naturally occurring sequences containing repetitive guanine motifs have the potential to form tetraplex DNA. Phytomonas serpens minicircle DNA shows some regions where one strand is composed mainly of G and T (GT regions). These regions contain several stretches of contiguous guanines. An oligonucleotide was constructed with the sequence corresponding to one of these regions (Phyto-GT). It was demonstrated by native gel electrophoresis and methylation protection that Phyto-GT forms tetramolecular (G4), bimolecular (G'2) and unimolecular (G4') structures stabilized through G-quartets. Tetraplex DNA formation by this sequence could have biological relevance as it can be formed in physiological conditions and GT regions comprise approximately one-third of P. serpens and Crithidia oncopelti minicircles.
