DNA-binding miniproteins based on zinc fingers. Assessment of the interaction using nanoporesElectronic supplementary information (ESI) available. See DOI: 10.1039/c7sc05441f

Obtaining artificial proteins that mimic the DNA binding properties of natural transcription factors could open new ways of manipulating gene expression at will. In this context it is particularly interesting to develop simple synthetic systems. Inspired by the modularity of natural transcription factors, we have designed synthetic miniproteins that combine the zinc finger module of the transcription factor GAGA and AT-hook peptide domains. These constructs are capable of binding to composite DNA sequences of up to 14 base pairs with high affinity and good selectivity. In particular, we have synthesized three different chimeras and characterized their DNA binding properties by electrophoresis and fluorescence anisotropy. We have also used, for the first time in the study of peptide-based DNA binders, nanopore force spectroscopy to obtain further data on the DNA interaction. We report a synthetic miniprotein that combines zinc finger modules of the transcription factor GAGA with the AT-hook peptide. This designed chimera binds to extended DNA sites with high affinity and selectivity, as shown by nanopore force spectroscopy.