The PNA-DNA hybrid I-motif: implications for sugar-sugar contacts in i-motif tetramerization.

ABSTRACT: We have created a hybrid i-motif composed of two DNA and two peptide nucleic acid (PNA) strands from an equimolar mixture of a C-rich DNA and analogous PNA sequence. Nano-electrospray ionization mass spectrometry confirmed the formation of a tetrameric species, composed of PNA-DNA heteroduplexes. Thermal denaturation and CD experiments revealed that the structure was held together by C-H+-C base pairs. High resolution NMR spectroscopy confirmed that PNA and DNA form a unique complex comprising five C-H+-C base pairs per heteroduplex. The imino protons are protected from D2O exchange suggesting intercalation of the heteroduplexes as seen in DNA4 i-motifs. FRET established the relative DNA and PNA strand polarities in the hybrid. The DNA strands were arranged antiparallel with respect to one

SUBMITTER: Modi S 

PROVIDER: S-EPMC1636347 | biostudies-literature | 2006

REPOSITORIES: biostudies-literature