Biomolecular mirror-image recognition: Reciprocal chiral-specific DNA binding of synthetic enantiomers of zinc finger domain from GAGA factor

To experimentally demonstrate the mirror-image recognition in protein and DNA interaction, we have designed a small DNA-binding peptide based on the zinc-finger domain of GAGA transcription factor. Circular dichroism data suggest that the conformations of peptide enantiomers as well as the DNA enantiomers have a mirror-image relationship. The gel mobility shift assay showed that the synthetic enantiomers of the peptide showed reciprocal chiral-specific interactions with the DNA; the natural L-peptide binds specifically with the natural D-DNA substrate, and the unnatural D-peptide binds specifically with the unnatural L-DNA substrate. The present data imply that the folding of the L- and D-enantiomers of the peptide as well as the DNA substrates are exact mirror images of each other in 3-D structure and biological activity, and generalize the chiral-specific nature of biomolecular interaction.