title: Activities of protein-deficient particles derived from 50-S ribosomal subunits by NH4Cl/ethanol treatment.
abstract: Protein-deficient ribosomal particles obtained by treatment of 50-S subunits from Escherichia coli ribosomes with 1 M NH4Cl and 50% ethanol contain less than 3% of proteins L7 and L12 and about 7% of proteins L10 and L11. Proteins L1, L5, L8/9 and L25 are also released during the treatment but in amounts accounting for less than 40%. The particles are able to form peptide bonds in different systems, such as 'fragment reaction', puromycin reaction and formation of dipeptides. They also bind N-acetylphenylalanyl-tRNA and phenylalanyl-tRNA non-enzymically but are unable to support any of the elongation-factor-dependent reactions tested. However, when methanol is present, they display up to 20% of the control EF-G-dependent GTP activities such as GTP hydrolysis and formation of the ternary complex EF-G-GuoPP(CH2)P-ribosome. The first activity is totally sensitive to the antibiotic thiostrepton while the formation of the ternary complex is unaffected by the drug. When measured by equilibrium dialysis the core particles are shown to be able to bind radioactive thiostrepton. The results show that protein L11 is not an absolute requirement either for peptidyl transferase activity or for the binding of thiostrepton, although in the last case the protein strongly enhances the ribosome affinity for the antibiotic.
mesh_terms: D000643:Ammonium Chloride; D001665:Binding Sites; D002458:Cell Fractionation; D004926:Escherichia coli / Q000378:metabolism*; D000431:Ethanol; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000378:metabolism; D006150:Guanine Nucleotides / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010445:Peptide Elongation Factors; D010458:Peptidyl Transferases / Q000378:metabolism; D010649:Phenylalanine; D012343:RNA, Transfer / Q000378:metabolism; D012269:Ribosomal Proteins / Q000502:physiology*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D013883:Thiostrepton / Q000494:pharmacology
chemical_list: D006150:Guanine Nucleotides; D010445:Peptide Elongation Factors; D012269:Ribosomal Proteins; D000643:Ammonium Chloride; D000431:Ethanol; D010649:Phenylalanine; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D010458:Peptidyl Transferases; D020963:GTP Phosphohydrolase-Linked Elongation Factors; D013883:Thiostrepton; D008274:Magnesium