title: Phosphorolytic error correction during transcription.
abstract: Escherichia coli DNA-directed RNA polymerase is shown to contain a novel phosphorolytic error correction activity which removes erroneous nucleotides, as rNDPs, from the 3'-end of the growing transcript. The activity we describe is biochemically similar to polynucleotide phosphorylase (PNP), yet in contrast to PNP is activated by Mn2+. We demonstrate that the activity, which is mediated by Pi, is dependent on the presence of an incorrectly incorporated nucleotide at the leading 3'-end of the transcript. The correction activity we describe exhibits a 4 x 10(4)-fold preference for the excision of incorrect nucleotides from the transcript. These findings suggest the possibility that RNA phosphorolysis may play a critical role in the process of transcriptional proofreading.
authors.affiliation: Department of Genetics, University of Washington, Seattle 98195.
authors.forename: R T
authors.initials: RT
authors.lastname: Libby
authors.forename: J A
authors.initials: JA
authors.lastname: Gallant
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics*; D008345:Manganese / Q000502:physiology; D010710:Phosphates / Q000378:metabolism; D011117:Polyribonucleotide Nucleotidyltransferase / Q000502:physiology*; D012318:RNA Polymerase I / Q000502:physiology*; D012329:RNA, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D016914:Ribonuclease H / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D010710:Phosphates; D012329:RNA, Bacterial; D012265:Ribonucleotides; D008345:Manganese; D012318:RNA Polymerase I; D011117:Polyribonucleotide Nucleotidyltransferase; D016914:Ribonuclease H