A proof-of-concept on transcription factor EL222 bioconjugation for targeted DNA cleavage

The development of site-specific artificial nucleases remains a significant challenge in chemical biology. Here, we report the design and biophysical characterization of a light-responsive protein-small molecule hybrid based on the EL222 transcription factor. Through protein bioconjugation, we converted the native LOV-HTH scaffold into a targeted pro-oxidant catalyst. Lysine functionalization with alkyl-dipicolylamine (C₁₀-DPA) moieties yielded a hybrid (DPA-EL222) with enhanced thermal stability (ΔT_M = +5 °C) and an increased affinity for its target DNA sequence. Functional assays demonstrate that DPA-EL222 maintains the structure and function of WT-EL222. Upon in situ recruitment of 2 equivalents of Cu(II), the hybrid selectively degrades its recognition DNA sequence but undergoes self-degradation in the absence of effective DNA binding. These results could pave the way for the development of highly selective artificial nucleases.