Bending of the Saccharomyces cerevisiae 5S rRNA gene in transcription factor complexes.

Bending of the yeast 5S rRNA gene by its transcription factors (TF) IIIA, IIIC, and IIIB has been investigated by two electrophoretic methods that exploit the anomalous mobility of bent DNA in tight gel networks. A minor bend is induced by TFIIIA, and a very strong bend, centered at its upstream DNA-binding site, is induced by TFIIIB. Despite binding to different DNA sequences on the 5S rRNA gene and the previously analyzed tRNA(Glu) gene, TFIIIB generates nearly identical bends in each site. Fully assembled transcription factor complexes bend the 5S rRNA gene in the same net direction as does TFIIIB alone.