Regiospecific function of the C‐terminal domain of RNA polymerase II in yeast

Abstract

The C‐terminal domain (CTD) of RPB1, the largest subunit of RNA polymerase II is comprised of repeating units of a seven amino acid sequence and is indispensible for function in eukaryotes. The aim of this study was to determine if repeats had specific function, dependent on their location within the sequence, or whether repeats were largely redundant. Using a library of precisely designed CTD mutants, a novel TET‐off system to control RPB1 expression, and phenotypic analysis in yeast we demonstrate that, in fact, different regions of the CTD exhibit different function. Specifically, we show differential sensitivity to various transcriptional inhibitors and can link phenotypes to the presence or absence of phosphorylatable serine residues. This study leads to a novel model for the assembly of CTD‐associating factors on the CTD during transcription. We also begin to use this library to identify changes in CTD‐associating protein recruitment to the CTD and to identify regions of the CTD important for processes such as mRNA processing and histone methylation.