Correlations between transcription of a yeast tRNA gene and transcription factor-DNA interactions

A partly purified fraction from Saccharomyces cerevisiae has a RNA polymerase III transcription factor activity and contains protein which binds specifically to two internal promoter regions of RNA polymerase III-transcribed genes. The influence of ionic strength and of dimethyl sulfoxide on specific binding to a S. cerevisiae tRNAleu3 gene has been analyzed by DNase I protection (footprinting) and by nitrocellulose filter binding. The effects of these agents on binding correlate with their effects on transcription and on the stability of transcription complexes. Dimethyl sulfoxide stabilizes binding and transcription complexes against dissociation by NaCl, with 10% dimethyl sulfoxide compensating for the addition of 50-60 mM NaCl. Binding of protein in the 5' proximal part of the S. cerevisiae tRNAleu3 gene is more NaCl-sensitive than binding in the 3' proximal part.