He has developed a methodology for isolating RNA binding proteins specific for desired targets using a phage display of a zinc finger library. These zinc fingers have been optimized for their target nucleic acid by molecularly shuffling zinc finger sequences. Dr. Darby is currently expressing these zinc fingers in tissue culture to assess their potential for blocking HIV replication. RNA polymerase III transcribes a number of essential cellular genes, such as transfer RNA and ribosomal 5S RNA genes. Viral genes are also transcribed by RNA polymerase III and activity is stimulated by viral infection.
Transcription initiation requires assembly of a multi-protein complex at the promoter.
The molecular mechanisms of activation from this complex is unknown. Dr. Darby is identifying the protein-protein interactions within the complex. A 14 amino acid segment of transcription factor IIIA is essential for activation of transcription, but is not required for DNA or RNA interaction. Currently under study is the interaction of one of these, TIP21, that has been shown to be required for RNA polymerase III transcription. Acids Res. , in press.