Multiple modes of RNA recognition by zinc finger proteins

Zinc finger proteins are generally thought of as DNA-binding transcription factors; however, certain classes of zinc finger proteins, including the common C2H2 zinc fingers, function as RNA-binding proteins. Recent structural studies of the C2H2 zinc fingers of transcription factor IIIA (TFIIIA) and the CCCH zinc fingers of Tis11d in complex with their RNA targets have revealed new modes of zinc finger interaction with nucleic acid. The three C2H2 zinc fingers of TFIIIA use two modes of RNA recognition that differ from the classical mode of DNA recognition, whereas the CCCH zinc fingers of Tis11d recognize specific AU-rich sequences through backbone atom interaction with the Watson-Crick edges of the adenine and uracil bases.