Novel interactions at the essential N-terminus of poly(A) polymerase that could regulate poly(A) addition in Saccharomyces cerevisiae

Addition of poly(A) to the 3' ends of cleaved pre-mRNA is essential for mRNA maturation and is catalyzed by Pap1 in yeast. We have previously shown that a non-viable Pap1 mutant lacking the first 18 amino acids is fully active for polyadenylation of oligoA, but defective for pre-mRNA polyadenylation, suggesting that interactions at the N-terminus are important for enzyme function in the processing complex. We have now identified proteins that interact specifically with this region. Cft1 and Pta1 are subunits of the cleavage/polyadenylation factor, in which Pap1 resides, and Nab6 and Sub1 are nucleic-acid binding proteins with known links to 3' end processing. Our results suggest a novel mechanism for controlling Pap1 activity, and possible models invoking these newly-discovered interactions are discussed. Structured summary of protein interactions: PAP1 binds to Fip1 by anti bait coimmunoprecipitation (View interaction) PAP1 binds to Fip1 by pull down (View interaction) PAP1 physically interacts with PTA1 by two hybrid (View interaction) PAP1 binds to Sub1 by pull down (View interaction) PAP1 physically interacts with Fip1 by two hybrid (View Interaction: 1, 2) PAP1 binds to Nab6 by pull down (View interaction) Nab6 physically interacts with PAP1 by two hybrid (View interaction) Cft1 binds to PAP1 by pull down (View interaction) PTA1 binds to PAP1 by pull down (View interaction) (C) 2012 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.