Evolution of iron(II)-finger peptides by using a bipyridyl amino acid

초록

We report the engineering of zinc-finger-like motifs containing the unnatural amino acid (2,2′-bipyridin-5-yl)alanine (Bpy-Ala). A phage-display library was constructed in which five residues in the N-terminal finger of zif268 were randomized to include both canonical amino acids and Bpy-Ala. Panning of this library against a nine-base-pair DNA binding site identified several Bpy-Ala-containing functional Zif268 mutants. These mutants bind the Zif268 recognition site with affinities comparable to that of the wild-type protein. Further characterization indicated that the mutant fingers bind low-spin FeII rather than ZnII. This work demonstrates that an expanded genetic code can lead to new metal ion binding motifs that can serve as structural, catalytic, or regulatory elements in proteins. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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