Specific RNA binding proteins constructed from zinc fingers.

A zinc finger library with degenerate alpha-helices was displayed on the surface of bacteriophage and proteins that bind human immunodeficiency virus type-1 (HIV-1) Rev response element stem loop IIB (RRE-IIB) RNA or 5S rRNA were isolated. DNA encoding affinity selected zinc fingers was shuffled by recombination in vitro to isolate proteins with higher RNA binding affinity. Proteins constructed in this way bind RNA specifically both in vitro and in vivo. These results demonstrate that RNA substrate specificity of zinc fingers can be changed through mutation of alpha-helices to construct novel RNA binding proteins.