title: Sequence motifs that distinguish ATP(CTP):tRNA nucleotidyl transferases from eubacterial poly(A) polymerases.
abstract: ATP(CTP):tRNA nucleotidyl transferases, tRNA maturing enzymes found in all organisms, and eubacterial poly(A) polymerases, enzymes involved in mRNA degradation, are so similar that until now their biochemical functions could not be distinguished by their amino acid sequence. BLAST searches and analysis with the program "Sequence Space" for the prediction of functional residues revealed sequence motifs which define these two protein families. One of the poly(A) polymerase defining motifs specifies a structure that we propose to function in binding the 3' terminus of the RNA substrate. Similar motifs are found in other homopolyribonucleotidyl transferases. Phylogenetic classification of nucleotidyl tranferases from sequenced genomes reveals that eubacterial poly(A) polymerases have evolved relatively recently and are found only in a small group of bacteria and surprisingly also in plants, where they may function in organelles.
authors.affiliation: Department of Cell Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
authors.forename: Georges
authors.initials: G
authors.lastname: Martin
authors.forename: Walter
authors.initials: W
authors.lastname: Keller
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000201:enzymology / Q000235:genetics; D020134:Catalytic Domain; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011062:Polynucleotide Adenylyltransferase / Q000737:chemistry / Q000235:genetics*; D012316:RNA Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D012316:RNA Nucleotidyltransferases; C023198:tRNA nucleotidyltransferase; D011062:Polynucleotide Adenylyltransferase