High-affinity homologous peptide nucleic acid probes for targeting a quadruplex-forming sequence from a MYC promoter element.
High-affinity homologous peptide nucleic acid probes for targeting a quadruplex-forming sequence from a MYC promoter element.
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DOI：
10.1021/bi700854r
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发表时间：
2007-08
期刊：
影响因子：
2.9
通讯作者：
Subhadeep Roy;F. Tanious;W. Wilson;Danith H. Ly;B. Armitage
中科院分区：
文献类型：
--
作者：
Subhadeep Roy;F. Tanious;W. Wilson;Danith H. Ly;B. Armitage
Guanine-rich DNA and RNA sequences are known to fold into secondary structures known as G-quadruplexes. Recent biochemical evidence along with the discovery of an increasing number of sequences in functionally important regions of the genome capable of forming G-quadruplexes strongly indicates important biological roles for these structures. Thus, molecular probes that can selectively target quadruplex-forming sequences (QFSs) are envisioned as tools to delineate biological functions of quadruplexes as well as potential therapeutic agents. Guanine-rich peptide nucleic acids have been previously shown to hybridize to homologous DNA or RNA sequences forming PNA-DNA (or RNA) quadruplexes. For this paper we studied the hybridization of an eight-mer G-rich PNA to a quadruplex-forming sequence derived from the promoter region of the MYC proto-oncogene. UV melting analysis, fluorescence assays, and surface plasmon resonance experiments reveal that this PNA binds to the MYC QFS in a 2:1 stoichiometry and with an average binding constant Ka = (2.0 +/- 0.2) x 10(8) M(-1) or Kd = 5.0 nM. In addition, experiments carried out with short DNA targets revealed a dependence of the affinity on the sequence of bases in the loop region of the DNA. A structural model for the hybrid quadruplex is proposed, and implications for gene targeting by G-rich PNAs are discussed.
