Banting and Best Department of Medical Research, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada-
Abstract: Glc7, the yeast protein phosphatase 1, is a component of the cleavage and polyadenylation factor -CPF-- Here we show that downregulation of Glc7, or its dissociation from CPF in the absence of CPF subunits Ref2 or Swd2, results in similar snoRNA termination defects- Overexpressing a C-terminal fragment of Sen1, a superfamily I helicase required for snoRNA termination, suppresses the growth and termination defects associated with loss of Swd2 or Ref2, but not Glc7- Suppression by Sen1 requires nuclear localization and direct interaction with Glc7, which can dephosphorylate Sen1 in vitro- The suppressing fragment, and in a similar manner full-length Sen1, copurifies with the snoRNA termination factors Nrd1 and Nab3, suggesting loss of Glc7 from CPF can be compensated by recruiting Glc7 to Nrd1-Nab3 through Sen1- Swd2 is also a subunit of the Set1c histone H3K4 methyltransferase complex and is required for its stability and optimal methyltransferase activity-