Hybridization of G-quadruplex-forming peptide nucleic acids to guanine-rich DNA templates inhibits DNA polymerase η extension.
Biochemistry
; 53(32): 5315-22, 2014 Aug 19.
Article
em En
| MEDLINE
| ID: mdl-25068499
ABSTRACT
The guanine quadruplex (G-quadruplex) is a highly stable secondary structure that forms in G-rich repeats of DNA, which can interfere with DNA processes, including DNA replication and transcription. We showed previously that short guanine-rich peptide nucleic acids (PNAs) can form highly stable hybrid quadruplexes with DNA. We hypothesized that such structures would provide a stronger block to polymerase extension on G-rich templates than a native DNA homoquadruplex because of the greater thermodynamic stability of the PNA-DNA hybrid structures. To test this, we analyzed the DNA primer extension activity of polymerase η, a translesion polymerase implicated in synthesis past G-quadruplex blocks, on DNA templates containing guanine repeats. We observed a PNA concentration-dependent decrease in the level of polymerase η extension to the end of the template and an increase in the level of polymerase η inhibition at the sequence prior to the G-rich repeats. In contrast, the addition of a complementary C-rich PNA that hybridizes to the G-rich repeats by Watson-Crick base pairing led to a decrease in the level of polymerase inhibition and an increase in the level of full-length extension products. The G-quadruplex-forming PNA exhibited inhibition (IC50=16.2±3.3 nM) of polymerase η DNA synthesis on the G-rich templates stronger than that of the established G-quadruplex-stabilizing ligand BRACO-19 (IC50=42.5±4.8 nM). Our results indicate that homologous PNA targeting of G-rich sequences creates stable PNA-DNA heteroquadruplexes that inhibit polymerase η extension more effectively than a DNA homoquadruplex. The implications of these results for the potential development of homologous PNAs as therapeutics for halting proliferating cancer cells are discussed.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DNA
/
DNA Polimerase Dirigida por DNA
/
Guanina
Limite:
Humans
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Estados Unidos