title: The nuclear poly(A) binding protein of mammals, but not of fission yeast, participates in mRNA polyadenylation.
abstract: The nuclear poly(A) binding protein (PABPN1) has been suggested, on the basis of biochemical evidence, to play a role in mRNA polyadenylation by strongly increasing the processivity of poly(A) polymerase. While experiments in metazoans have tended to support such a role, the results were not unequivocal, and genetic data show that theS. pombeortholog of PABPN1, Pab2, is not involved in mRNA polyadenylation. The specific model in which PABPN1 increases the rate of poly(A) tail elongation has never been examined in vivo. Here, we have used 4-thiouridine pulse-labeling to examine the lengths of newly synthesized poly(A) tails in human cells. Knockdown of PABPN1 strongly reduced the synthesis of full-length tails of ∼250 nucleotides, as predicted from biochemical data. We have also purifiedS. pombePab2 and theS. pombepoly(A) polymerase, Pla1, and examined their in vitro activities. Whereas PABPN1 strongly increases the activity of its cognate poly(A) polymerase in vitro, Pab2 was unable to stimulate Pla1 to any significant extent. Thus, in vitro and in vivo data are consistent in supporting a role of PABPN1 but notS. pombePab2 in the polyadenylation of mRNA precursors.
authors.affiliation: Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Kühn
authors.affiliation: Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Buschmann
authors.affiliation: Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
authors.forename: Elmar
authors.identifier: 0000-0003-2504-0677
authors.initials: E
authors.lastname: Wahle
mesh_terms: D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D011061:Poly A / Q000096:biosynthesis / Q000235:genetics*; D039122:Poly(A)-Binding Protein I / Q000235:genetics* / Q000378:metabolism; D039102:Poly(A)-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D026723:Polyadenylation; D011062:Polynucleotide Adenylyltransferase / Q000235:genetics* / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D007527:Isoenzymes; C576588:PABPN1 protein, human; C582314:Pab2 protein, S pombe; D039122:Poly(A)-Binding Protein I; D039102:Poly(A)-Binding Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D029702:Schizosaccharomyces pombe Proteins; D011061:Poly A; D011062:Polynucleotide Adenylyltransferase
keywords: mRNA polyadenylation; poly(A) binding protein; poly(A) polymerase; pre-mRNA 3′; processing