The Med8 mediator subunit interacts with the Rpb4 subunit of RNA polymerase II and Ace2 transcriptional activator in Schizosaccharomyces pombe

Abstract

Several proteins are involved in separation of cells following division. However, their mutual interactions leading to cell separation is complex and not well understood. To explore the protein network that regulates this process at the transcriptional level in Schizosaccharomyces pombe, we have investigated the role of three proteins Med8, Rpb4 and Ace2. Using genetic and biochemical approaches we demonstrate that Ace2 binds Med8, which in turn interacts with Rpb4. We have delineated regions of Med8 and Rpb4 involved in their binding. We show that Med8 carboxyl-terminal region is necessary for its interaction with Rpb4 and can partially complement the sep15-598 mutant. Our results suggest that Med8 mediator subunit is involved in transmitting regulatory information from Ace2 to RNA polymerase II via Rpb4.