Eiko Otaka

Molecular and metabolic properties of messenger RNA from normal and T2-infected Escherichia coli*

1 A method has been developed for the preparation of “undegraded“ messenger RNA from normal and T2-phage infected E. coli cells. On methylated albumin columns the RNA was heterogeneous, and could be fractionated into four main components with sedimentation coefficients of 8 s (M-RNA-I), 10 to 12 s (M-RNA-II), 19 to 21 s plus 13 s (M-RNA-III) and 23 to 30 s (M-RNA-IV), respectively. 2 The time course of the incorporation of [ 14 C]uracil into M-RNA-II, M-RNA-III and M-RNA-IV, or of the disappearance of radioactivity from these RNAs prelabeled with the isotopes, has been investigated. The radioactivity in these three components increased or decreased in a parallel fashion, indicating that no precursor-product relationship exists among them. 3 Chloramphenicol inhibited the synthesis of M-RNA-IV without preventing synthesis of M-RNA-II and M-RNA-III. 4 The specific ability of M-RNA-IV to associate with 70 s ribosomes in vitro has been demonstrated. Neither M-RNA-II nor M-RNA-III has such an ability. The RNA-ribosome complex has a sedimentation coefficient about 10 to 15 s higher than the normal 70 s ribosome.

A deoxyribonucleic acid-protein complex having DNA-polymerase and RNA-polymerase activities in cell-free extracts of Escherichia coli

Abstract 1. 1. A deoxyribonucleoprotein, found in extracts of Escherichia coli B(H), has been investigated with respect to its role in DNA and RNA synthesis. 2. 2. A deoxyribonucleoprotein in ribosome-free cell extract could be separated from the other cellular components either with gel filtration or zone electrophoresis. 3. 3. The isolated deoxyribonucleoprotein was composed of roughly 80% of DNA a and 20% of protein. 4. 4. Association of DNA polymerase (deoxynucleosidetriphosphate: DNA deoxynucleotidyltransferase, EC 2.7.7.7) and RNA polymerase (nucleosidetriphosphate: RNA nucleotidyltransferase (DNA dependent), EC 2.7.7.6) with this deoxyribonucleoprotein has been demonstrated. 5. 5. DNA polymerase and RNA polymerase, purified from E. coli extract, had an ability to form a complex with DNA.

Synthesis of ribonucleic acids in microbial cells. I. Ribosomal ribonucleic acid synthesis in growing bacterial cells.

A procedure of separating nucleic acids and nucleoproteins from bacterial extracts by DEAE-column chromatography has been described. The method allows to separate s-RNA, “DNA”, several classes of ribosomes and their possible precursors. The study of incorporation of isotopic precursors into nucleic acids in growing cells of Escherichia coli and Bacillus cereus has suggested that the ribosomal RNA is first formed on DNA and finally built up to complete ribosomal particles via sequential intermediate steps. The intermediates including a “DNA-RNA complex” are accumulated when protein synthesis is inhibited by 8-azaguanine or chloramphenicol. The DNA-RNA complex is sensitive either to DNAase or to RNAase. Judged from the results of a degradation experiment with DNAase, the molecular size of the RNA component of the complex is fairly small.