Polynucleotide phosphorylase functions both as a 3′ → 5′ exonuclease and a poly(A) polymerase in Escherichia coli

摘要: Abstract In vitro, polynucleotide phosphorylase of Escherichia coli can both synthesize RNA by using nucleotide diphosphates as precursors and exonucleolytically degrade in the presence inorganic phosphate. However, because high vivo concentration phosphate exponentially growing cells, it has been assumed that enzyme works exclusively an exonuclease. Here we demonstrate that, contrary to this prediction, not only synthesizes long, highly heteropolymeric tails vivo, but also accounts for all observed residual polyadenylylation poly(A) polymerase I deficient strains. In addition, is responsible adding C U residues are found cultures wild type E. coli.