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Updated: Jun 14, 2026

Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains
Published on: March 25, 2015
Calcium ion responsive DNA binding in a zinc finger fusion protein
Akira Onoda1, Nozomi Arai, Naoto Shimazu
1Department of Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo, 162-8601, Japan.
Abstract:
Zinc finger fusion proteins, having a Ca-binding site from troponin C, were created to develop Ca-responsive regulation of DNA binding. The typical zinc finger folding of a novel fusion protein with a single finger, F2-Tn, was investigated using UV-vis spectroscopy of the Co-substituted form and CD experiments. Detailed structural analyses of F2-Tn/Zn2+ using NMR experiments and structural calculations clarify that our fusion protein gives a native zinc finger folding with the artificial Ca-binding domain intervening two helices. The Ca-responsive DNA-binding affinity of troponin-fused protein with two fingers (using F1F2-Tn) was investigated by electrophoretic mobility shift assay (EMSA). EMSA analyses of F1F2-Tn were performed under the conditions of various concentrations of the Ca ion. F1F2-Tn has a Kd value of 5.8 nM in the absence of Ca ion and shows a higher Kd value of 13 nM in the presence of 100 equiv of Ca ion. The artificially designed fusion zinc finger protein with a Ca-binding domain has Ca-responsive DNA-binding affinity. It is leading to a better understanding of the construction of zinc finger-based artificial transcriptional factors with a Ca switch.
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