title: The origin and early evolution of nucleic acid polymerases.
abstract: The hypothesis that vestiges of the ancestral RNA-dependent RNA polymerase involved in the replication of RNA genomes of Archean cells are present in the eubacterial RNA polymerase beta' subunit and its homologues is discussed.  We show that in the DNA-dependent RNA polymerases from the three cellular lineages a very conserved sequence of eight amino acids also found in a small RNA-binding site previously described for the E. coli polynucleotide phosphorylase and the S1 ribosomal protein is present.  The optimal conditions for the replicase activity of the avian myeloblastosis virus reverse transcriptase are presented.  The evolutionary significance of the in vitro modifications of substrate and template specificities of RNA polymerases and reverse transcriptases is also discussed.
authors.affiliation: Departamento de Biologia, UNAM, Mexico, D.F.
authors.forename: A
authors.initials: A
authors.lastname: Lazcano
authors.forename: V
authors.initials: V
authors.lastname: Llaca
authors.forename: R
authors.initials: R
authors.lastname: Cappello
authors.forename: V
authors.initials: V
authors.lastname: Valverde
authors.forename: J
authors.initials: J
authors.lastname: Oró
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001105:Archaea / Q000201:enzymology; D005075:Biological Evolution; D012321:DNA-Directed RNA Polymerases / Q000032:analysis / Q000737:chemistry*; D004926:Escherichia coli / Q000201:enzymology; D005051:Eubacterium / Q000201:enzymology; D005057:Eukaryotic Cells / Q000201:enzymology; D008969:Molecular Sequence Data; D000069497:Origin of Life; D011117:Polyribonucleotide Nucleotidyltransferase / Q000032:analysis / Q000737:chemistry; D012324:RNA-Dependent RNA Polymerase / Q000032:analysis / Q000737:chemistry*; D012194:RNA-Directed DNA Polymerase / Q000032:analysis / Q000737:chemistry; D013379:Substrate Specificity; D013698:Templates, Genetic; D014780:Viruses / Q000201:enzymology
chemical_list: D000596:Amino Acids; D012324:RNA-Dependent RNA Polymerase; D012194:RNA-Directed DNA Polymerase; D012321:DNA-Directed RNA Polymerases; D011117:Polyribonucleotide Nucleotidyltransferase