Answer Happy

Which two reactions could you compare to assess whether a
species specific interaction between TFIIB and RNA polymerase is
needed for transcription?
The locations of the TATA box in the genes of two species of yeast, Saccharomyces pombe and Saccharomyces cerevisiae , differ dramatically. The TATA box of S. pombe is about 30 nucleotides upstream of the start site, similar to the location in most other eukaryotic cells. However, the TATA box of S. cerevisiae is 40 to 120 nucleotides upstream of the start site. To better understand what sets the start site in these organisms, researchers at Stanford University conducted a series of experiments to determine which components of the transcription apparatus of these two species could be interchanged (Y. Li et al. 1994. Science 263:805-807). In these experiments, different transcription factors and RNA polymerases were switched in S. pombe and S. cerevisiae , and the effects of the switch on the level of RNA synthesis and on the start point of transcription were observed. The results from one set of experiments are shown in the table below. Components CTFIIB, CTFIIE, CTFIIF, and CTF IH are transcription factors from S. cerevisiae. Components PTFIIB, PTFIIE, PTFIIF, and PTFIIH are transcription factors from S. pombe. Components Pol II and pPol Il are RNA polymerase Il from S. cerevisiae and S. pombe, respectively. The table indicates whether the component was present (+) or missing (-) in the experiment. In the accompanying gel, the presence of a band indicates that RNA was produced and the position of the band indicates whether it was the length predicted when transcription begins 30 bp downstream from the TATA box or from 40 to 120 bp downstream from the TATA box. Experiment 5 1 2 3 6 7 + + Components CTFIIE CTFIIH + CTFIIF CTFIIB cPol 11 pPol 11 PTFIIB PTFIIF + PTFIIH + PTFIIE Experiment 3 4 5 1 2 6 7 Transcription at S. pombe start site (30 bp downstream from TATA box -- Transcription at S. cerevisiae start site (40-120 bp downstream from TATA box Gel Results

Which two reactions could you compare to assess whether a species specific interaction between TFIIB and RNA polymerase is needed for transcription? pPol II, PTFIIB, PTFIIF + CTFIIH + PTFIIE pPol II, PTFIIB, PTFIIF + PTFIIH + CTFIIE pPol II, CTFIIB, PTFIIF + PTFIIH + PTFIIE pPol II, PTFIIB, CTFIIF + PTFIIH + PTFIIE pPol II, PTFIIB, PTFIIF + PTFIIH + PTFIIE