title: "Compartmentalization" of Escherichia coli ribosomes and ribonucleic acid.
abstract: Escherichia coli spheroplasts lysed by Brij 58 and deoxycholate were separated into supernatant (S) and membrane fractions by low-speed centrifugation. The membrane fraction was further divided into that which was releasable by deoxyribonuclease (fraction D) and that which was not (M). In the presence of 10(-2)m Mg(2+), the S, D, and M fractions contained, respectively, 60, 20, and 20% of the total cellular ribonucleic acid (RNA). Ribosomal and transfer RNA (rRNA, tRNA) were found in each fraction. The M + D fraction RNA was labeled more by a pulse label. Incorporation of uracil into the D fraction continued only as long as the uptake of exogenous uracil, suggesting that this was a major primary site of RNA synthesis. From pulse-labeled cells, each fraction contained precursor rRNA, and there was a 10S RNA in the M fraction. Ninety per cent of the ribosomal subunits and the ribosomal precursor particles, 26 and 43S, were in the S fraction. Precursor RNA (17S) was found in the 26S precursor particles. The D fraction contained 38% of the polysomes (this does not consider polysomes, if any, of the M fraction) which were labeled four times as much as the supernatant polysomes by a 1-min pulse of uracil. These results are interpreted to mean that new RNA is associated with a cytoplasmic membrane-RNA polymerase-DNA complex.
mesh_terms: D001433:Bacteriolysis; D001647:Bile Acids and Salts; D002247:Carbon Isotopes; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D002498:Centrifugation; D002499:Centrifugation, Density Gradient; D004269:DNA, Bacterial / Q000096:biosynthesis; D003851:Deoxyribonucleases; D004926:Escherichia coli / Q000166:cytology* / Q000378:metabolism; D008854:Microscopy, Electron; D012316:RNA Nucleotidyltransferases / Q000096:biosynthesis; D012329:RNA, Bacterial / Q000032:analysis* / Q000096:biosynthesis; D012335:RNA, Ribosomal / Q000032:analysis; D012343:RNA, Transfer / Q000032:analysis; D012270:Ribosomes / Q000032:analysis*; D013104:Spheroplasts; D013395:Sucrose; D013501:Surface-Active Agents; D013941:Thymine / Q000378:metabolism; D014316:Tritium; D014498:Uracil / Q000378:metabolism
chemical_list: D001647:Bile Acids and Salts; D002247:Carbon Isotopes; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D013501:Surface-Active Agents; D014316:Tritium; D014498:Uracil; D013395:Sucrose; D012343:RNA, Transfer; D012316:RNA Nucleotidyltransferases; D003851:Deoxyribonucleases; D013941:Thymine