title: Stimulation of poly(A) polymerase through a direct interaction with the nuclear poly(A) binding protein allosterically regulated by RNA.
abstract: During polyadenylation of mRNA precursors in metazoan cells, poly(A) polymerase is stimulated by the nuclear poly(A) binding protein PABPN1. We report that stimulation depends on binding of PABPN1 to the substrate RNA directly adjacent to poly(A) polymerase and results in an approximately 80-fold increase in the apparent affinity of poly(A) polymerase for RNA without significant effect on catalytic efficiency. PABPN1 associates directly with poly(A) polymerase either upon allosteric activation by oligo(A) or, in the absence of RNA, upon deletion of its N-terminal domain. The N-terminal domain of PABPN1 may function to inhibit undesirable interactions of the protein; the inhibition is relieved upon RNA binding. Tethering of poly(A) polymerase is mediated largely by the C-terminal domain of PABPN1 and is necessary but not sufficient for stimulation of the enzyme; an additional interaction dependent on a coiled-coil structure located within the N-terminal domain of PABPN1 is required for a productive interaction.
authors.affiliation: Institut für Biochemie and Institut für Biotechnologie, Martin-Luther-Universität Halle, Kurt-Mothes-Strasse 3, D-06120 Halle, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Kerwitz
authors.forename: Uwe
authors.initials: U
authors.lastname: Kühn
authors.forename: Hauke
authors.initials: H
authors.lastname: Lilie
authors.forename: Anne
authors.initials: A
authors.lastname: Knoth
authors.forename: Till
authors.initials: T
authors.lastname: Scheuermann
authors.forename: Henning
authors.initials: H
authors.lastname: Friedrich
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Schwarz
authors.forename: Elmar
authors.initials: E
authors.lastname: Wahle
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism*; D002942:Circular Dichroism; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011061:Poly A / Q000378:metabolism*; D026723:Polyadenylation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D011061:Poly A; D012313:RNA