title: Halobacterium cutirubrum ribosomes. Properties of the ribosomal proteins and ribonucleic acid.
abstract: 1. The 30S ribosomal subunit of the extreme halophile Halobacterium cutirubrum is unstable and loses 75% of its ribosomal protein when the 70S ribosome is dissociated into the two subunits. A stable 30S subunit is obtained if the dissociation of the 70S particle is carried out in the presence of the soluble fraction. 2. A fractionation procedure was developed for the selective removal of groups of proteins from the 30S and 50S subunits. When the ribosomes, which are stable in 4m-K(+) and 0.1m-Mg(2+), were extracted with low-ionic-strength buffer 75-80% of the 30S proteins and 60-65% of the 50S proteins as well as the 5S rRNA were released. The proteins in this fraction are the most acidic of the H. cutirubrum ribosomal proteins. Further extraction with Li(+)-EDTA releases additional protein, leaving a core particle containing either 16S rRNA or 23S rRNA and about 5% of the total ribosomal protein. The amino acid composition, mobility on polyacrylamide gels at pH4.5 and 8.7, and the molecular-weight distribution of the various protein fractions were determined. 3. The s values of the rRNA are 5S, 16S and 23S. The C+G contents of the 16S and 23S rRNA were 56.1 and 58.8% respectively and these are higher than C+G contents of the corresponding Escherichia coli rRNA (53.8 and 54.1%).
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000302:isolation & purification*; D002247:Carbon Isotopes; D004492:Edetic Acid; D004591:Electrophoresis, Polyacrylamide Gel; D006217:Halobacterium / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008094:Lithium; D008239:Lysine / Q000378:metabolism; D008274:Magnesium; D008970:Molecular Weight; D011188:Potassium; D012335:RNA, Ribosomal / Q000302:isolation & purification*; D012270:Ribosomes / Q000032:analysis*
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D002247:Carbon Isotopes; D012335:RNA, Ribosomal; D008094:Lithium; D004492:Edetic Acid; D008274:Magnesium; D008239:Lysine; D011188:Potassium