Mutational analysis of mammalian poly(A) polymerase identifies a region for primer binding and catalytic domain, homologous to the family X polymerases, and to other nucleotidyltransferases.
We have tested deletion and substitution mutants of bovine poly(A) polymerase, and have identified a small region that overlaps with a nuclear localization signal and binds to the RNA primer. Systematic mutagenesis of carboxylic amino acids led to the identification of three aspartates that are essential for catalysis. Sequence and secondary structure comparisons of regions surrounding these aspartates with sequences of other polymerases revealed a significant homology to the palm structure of DNA polymerase beta, terminal deoxynucleotidyltransferase and DNA polymerase IV of Saccharomyces cerevisiae, all members of the family X of polymerases. This homology extends as far as cca: tRNA nucleotidyltransferase and streptomycin adenylyltransferase, an antibiotic resistance factor.
Martin
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G
Department of Cell Biology, University of Basel, Basel, Switzerland.
Keller
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W
D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000201:enzymology; D002417:Cattle; D004253:DNA Nucleotidylexotransferase / Q000737:chemistry; D004256:DNA Polymerase I / Q000737:chemistry; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry; D015801:Helminth Proteins / Q000737:chemistry; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000145:classification; D011062:Polynucleotide Adenylyltransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D012313:RNA / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014982:Xenopus laevis
D005656:Fungal Proteins; D015801:Helminth Proteins; D012322:RNA Precursors; C034477:RNA primers; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D001224:Aspartic Acid; D012313:RNA; D009713:Nucleotidyltransferases; D011062:Polynucleotide Adenylyltransferase; D004253:DNA Nucleotidylexotransferase; D004256:DNA Polymerase I; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase; C084892:POL4 protein, S cerevisiae