Biochemical and Genetic Characterization of the Transcription Elongation Factor TFIIS from the Yeast Saccharomyces Cerevisiae

Book excerpt: Regulation of the process of transcriptional elongation is an important control mechanism in the expression of some genes. To fully understand this form of regulation will require better understanding of the functions of transcription elongation factors. The goal of this work was to characterize the transcription elongation factor TFIIS from Saccharomyces cerevisiae, originally called P37. I demonstrated that, like the mammalian TFIIS proteins, the yeast protein stimulates RNA polymerase II to cleave the nascent RNA transcript and to read-through an intrinsic block to elongation. Investigation of the protein-protein contacts between TFIIS and RNA polymerase II indicated that the carboxyl-terminal domain of the largest subunit, subunit four, and subunit seven of the polymerase are not required for TFIIS to promote cleavage and read-through by the polymerase. In addition the carboxyl-terminal half of the yeast TFIIS protein is sufficient for both of these in vitro activities. This result is consistent with the previous results demonstrating the carboxyl-terminus of mouse TFIIS was sufficient to activate RNA polymerase in vitro.