Studies of the ribonucleic acid polymerase from Escherichia coli. V. Studies of its complexes with polyribonucleotides.

Formation of homopolymers of ribonucleotides by polynucleotide phosphorylase is well known (1, 2). In this reaction, a polymerization of ribonucleoside diphosphates occurs with the elimination of inorganic orthophosphate. Reactions involving formation of polyadenylic acid from adenosine triphosphate with elimination of an inorganic pyrophosphate group have been described with enzymes from several sources (3-6). Such a reaction, catalyzed by a polymerase from calf thymus nuclei (3, 4), is dependent upon polynucleotide primer which contains a high proportion of adenylic acid. An enzyme obtained from ribosomal particles of Escherichia coli (5) and one from chorioallantoic membranes of chick embryos (6) catalyze formation of polyadenylic acid from adenosine triphosphate in the presence of certain ribonucleic acid preparat,ions. A reaction catalyzed by purified RNA polymerase fractions of E. coli and involving polymerization of single ribonucleoside triphosphates in the presence of DNA and divalent cation has been noted (7-9). This paper describes more detailed studies of the homopolymerization reaction carried out by the RNA polymerase purified in our laboratory (10). Since formation of polyadenylic acid proceeds at a very rapid rate, most of the studies have been concerned with this homopolymer. Evidence is also presented that polyuridylic acid and polycytidylic acid may be formed, and that RNA as well as DNA stimulates the reaction.