Title: Dissecting the interactions between Pol II/TFIIE and TFIIH during transcription initiation in Saccharomyces cerevisiae
Abstract:
During transcription initiation in Saccharomyces cerevisiae, Pol II, and its general transcription factors (GTFs) assemble upstream of transcription start sites (TSSs) to form the pre-initiation complex (PIC). The PIC then selects TSSs by a unidirectional scanning mechanism. Structural studies show that a TFIIH component Tfb3 links TFIIH to the rest of the PIC via its interactions with Pol II and TFIIE. Activities within the PIC that influence TSS selection can do so by control of initiation efficiency at individual TSSs and by control of TSS scanning (either rate of scanning or scanning processivity). How factors in the PIC at the interface of Pol II and TFIIH contribute to these different activities needs to be clarified. We demonstrate that a specific connection between Tfb3 and Rpb7 is critical for proper TSS selection. Likewise, previous genetic screens from our lab report the identification of tfb3 and tfa1 alleles for putative TSS selection mutants and demonstrate that a subset confers TSS defects in vivo. These novel alleles, many of which have residues conserved from budding yeast to humans, show TSS shifts at the model promoter ADH1 demonstrated by primer extension results. In addition to primer extension and phenotyping analysis, we are mapping TSSs genome-wide in these mutants to quantitatively understand how they alter initiation across all genomic promoters (TSS-sequencing). Promoter-level data from our genome-wide TSS mapping provides a quantitative window into phenotypic classes of different initiation mutants. Currently, we are critically analyzing the sequencing data to determine if Pol II-TFIIH interface mutants work with the Pol II active site to promote initiation efficiency or contribute to TFIIH functions and promoter scanning efficiency.
Kaplan Lab
Friday, December 8th, 2023
12:00PM
Lagnley A219B