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At least 19 recordsLinked to original sources
PubMed1975

Cluster of genes in Escherichia coli for ribosomal proteins, ribosomal RNA, and RNA polymerase subunits.

The transducing phage lambdarifd18 isolated by Kirschbaum and Konrad [(1973 J. Bacteriol. 116, 517-526] was found to carry structural genes for several 50S ribosomal proteins and 16S and 23S rRNA. It has previously been demonstrated [Kirschbaum & Scaife (1974) Mol. Gen. Genet. 132, 193-201] that this phage carries genes for the DNA-dependent RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) subunits beta and beta'. Thus, the region of the E. coli chromosome carried by lambdarifd18 contains a cluster of genes essential for transcription and translation.

Bacterial Proteins↗
PubMed1977

Functional roles of 50-S ribosomal proteins.

Ribosomal proteins previously inactivated by treatment with fluorescein isothiocyanate have been incorporated into 50-S ribosomal subunits during reconstitution from particles disassembled by 2 M LiCl in the presence of an excess of the modified proteins. The reconstituted particles show alterations in some functional activities resulting from the incorporation of the inactive ribosomal proteins added exogenously. Of the fluorescein-isothiocyanate-treated proteins incorporated, L24 and L25 drastically affect all the activities tested and these proteins possibly play a fundamental role in determining the overall structure of the particle. Proteins L16 and L10 are apparently involved both in the GTP hydrolysis dependent on elongation factor G and in peptidyl transferase activity but the modified protein L11 only affects GTPase activity indirectly and interferes with the ribosome assembly process involving proteins L7 and L12. Protein L1 may be involved with peptidyl transferase activity while proteins L7 and L12, in agreement with many reports in the literature, affect the factor-dependent hydrolysis of GTP.

Escherichia coli↗
PubMed1977

Exchange of individual ribosomal proteins between ribosomes as studied by heavy isotope-transfer experiments.

Whether the individual ribosomal proteins undergo exchange between robosomes in vivo during cell growth was examined using heavy isotope transfer methodology. E. coli was grown first in a heavy isotope medium in the presence of [3H] leucine and then transferred to normal medium and allowed to grow for one generation in the presence of [14C] leucine. The "heavy" and "light" ribosomes that were present in such cells were separated by sedimentation and the ribosomal proteins resolved by two-dimensional gel electrophoresis. The individual proteins were burnt in O2 and their contents of [3H] and [14C] labels determined. From the analysis of the data we find that the great majority of the ribosomal proteins of E. coli does not undergo exchange during cell growth. Proteins which were found to exchange to varying levels in different transfer experiments were S1, S2, L7/L12, L9, L10 and L33. All of them except L9 exchanged to the same levels in control experiments in which separately grown heavy and light cells were mixed and processed. These proteins therefore undergo exchange during cell breakage and ribosome isolation. Protein L9 consistently showed appreciably greater exchange in transfer experiments as compared to the controls suggesting that it may exchange in vivo.

Bacterial Proteins↗
PubMed1979

The polysomal proteins of L cells. Discrimination between the structural ribosomal proteins, the exchangeable ribosomal proteins and the non-ribosomal proteins by two-dimensional dodecylsulfate electrophoresis and autoradiography.

Three groups of proteins can be clearly discriminated in the total protein of L cell polysomes by selective labelling in the presence of low doses of actinomycin D and two-dimensional polyacrylamide/dodecylsulfate gel electrophoresis followed by autoradiography: (a) structural ribosomal proteins which are not labelled in the presence of actinomycin D and form stained non-radioactive spot in gels; (b) exchangeable ribosomal proteins which are labelled in the presence of actinomycin D and stained radioactive spots; (c) non-ribosomal proteins which are detectable only by autoradiography of gels. The large and small subunits of L cell ribosomes contain respectively 45 and 34 ribosomal proteins with molecular weights less than or equal to 50 000; seven of the large subunit proteins and nine of the small subunit proteins are exchangeable. Most of the non-ribosomal proteins migrate in the region of the related to the separation of the ribosomal proteins of mammalian cells and the possible significance of the presence of non-ribosomal proteins in polysomes are discussed.

Dactinomycin↗
PubMed1979

The pools of ribosomal proteins and ribosomal ribonucleic acids during relaxed control of Escherichia coli A19 (Hfr, rel met rns).

The soluble fraction extracted from Escherichia coli A19 (Hfr, rel met rns) during early and late times of phenotypic and genotypic induced relaxed control have been examined for the possible accumulation of ribosomal proteins (r-proteins) and rRNA species during this time of unbalanced macromolecular synthesis. Ribosomal proteins and rRNA species were not found to accumulate within the soluble fraction at any time during this period of relaxed control; even after the typical rRNA accumulation had ceased, r-proteins did not accumulate. It is concluded, from these and related observations, that the r-proteins and rRNA species known to be produced during relaxation must immediately associate to form the unusual ribonucleoprotein particles (e.g. 'relaxed particles' and 'chloramphenicol particles') characteristic of periods of relaxed control. Since r-proteins do not accumulate even when net RNA accumulation halts, it appears that some elements of the normal, basic co-ordination between rRNA and r-protein synthesis/stability persist even during relaxed control.

Centrifugation, Density Gradient↗
PubMed1979

Expression of ribosomal protein genes cloned in a hybrid plasmid in Escherichia coli: gene dosage effects on synthesis of ribosomal proteins and ribosomal protein messenger ribonucleic acid.

Using ColE1-TnA hybrid plasmid RSF2124 as the cloning vector, we constructed a hybrid plasmid, pNO1001, which carried seven ribosomal protein (r-protein) genes in the spc operon together with their promoter. The plasmid also carried three r-protein genes which precede the spc operon, but did not carry the bacterial promoter for these genes. Expression of r-protein genes carried by pNO1001 was studied by measuring messenger ribonucleic acid and r-protein synthesis in cells carrying the plasmid. It was found that the messenger ribonucleic acid for all the promoter-distal r-protein genes was synthesized in large excess relative to messenger ribonucleic acid from other chromosomal r-protein genes which are not carried by the plasmid. However, only the two promoter-proximal r-proteins, L14 and L24, were markedly overproduced. The absence of large gene dosage effects on the synthesis of other distal proteins appeared to be due, at least in part, to preferential inactivation and/or degradation of the distal message which codes for these proteins; in addition, some preferential inhibition of translation of the distal message might also have been involved. Overproduced L14 and L24 were found to be degraded in recA+ strains at both 30 and 42 degrees C; in recA strains, the degradation took place at 42 degrees C but was very slow or absent at 30 degrees C. The recA strains carrying pNO1001 failed to form colonies at 30 degrees C, presumably because of overaccumulation of r-proteins. The results suggest that degradation of excess r-proteins is an important physiological process.

Alleles↗
PubMed1978

Yeast ribosomal proteins. I. Characterization of cytoplasmic ribosomal proteins by two-dimensional gel electrophoresis.

The cytoplasmic 80s ribosomal proteins from the cells of yeast Sachharomyces cerevisiae were analysed by SDS two-dimensional polyacrylamide gel electrophoresis. Seventyfour proteins were identified and consecutively numbered from 1 to 74. Upon oxidation of the 80s proteins with performic acid, ten proteins (no. 15, 20, 35, 40, 44, 46, 49, 51, 54 and 55) were dislocated on the gel without change of the total number of protein spots. Five proteins (no. 8, 14, 16, 36 and 74) were phosphorylated in vivo as seen in 32P-labelling experiments. The large and small subunits separated in low magnesium medium were analyzed by the above gel electrophoresis. At least forty-five and twenty-eight proteins were assumed to be in the large and small subunits, respectively. All proteins found in the 80s ribosomes, except for no. 3, were detected in either subunit without appearance of new spots. The acidic protein no. 3 seems to be lost during subunit dissociation.

Autoradiography↗
PubMed1977

Improved electrophoretic and immunochemical techniques for the identification and characterization of mutant proteins, applied to ribosomal protein S8 in Escherichia coli mutants.

The ribosomal proteins of 11 mutants which are sensitive to starvation at elevated temperature and of 36 transductants derived from them were studied with several electrophoretic, immunochemical and proteinchemical methods. The following results were obtained: (1) Ribosomal protein S8 is altered in three of these mutants. (2) The amino acid exchange in proteins S8 of mutant N4128 is Glu leads to Lys in position 59 of the protein chain. (3) Temperature sensitivity and inability to recover from starvation at elevated temperatures are caused by the same mutational event which is, however, unrelated to the alteration in protein S8. Several electrophoretic and immunological procedures were applied during the characterization of these mutants. A modified immunoelectrophoresis on cellulose acetate gels was developed, and proved to be the most applicable procedure for the detection of mutationally altered ribosomal proteins. This procedure may gain general importance for detecting mutational alterations in other proteins.

Amino Acid Sequence↗
PubMed1977

Exchange of ribosomal proteins among the ribosomes of Escherichia coli.

The exchange of ribosomal proteins among ribosomes of E. coli has been measured, using a density label technique. As expected most of the proteins do not exchange appreciably. However a substantial fraction of each of proteins S1, S2, S21, L7/L12, L9, L10, L11, L26 and L33 is found to exchange, but exchange of S1, S2, L7/L12, L10, L11 and L26 is found to occur in vitro after lysis of the cells, and therefore it is not possible to say whether or not these proteins also exchange in vivo. tin contrast S21, l9 and L33 do not exchange after lysis of the cells and we therefore conclude that these proteins exchange in vivo. The maximum level of exchange of S21, L9 and L33 is attained so rapidly that we were unable to show whether or not it was dependent on protein synthesis.

Bacterial Proteins↗
PubMed1977

On the control of ribosomal protein biosynthesis in Escherichia coli. I. Studies on ribosomal protein biosynthesis in amino acid-starved cells.

The rate of individual ribosomal protein synthesis relative to total protein synthesis has been determined in Escherichia coli rel+ and rel- cells, under valyltRNA deprivation. These strains have a temperature-sensitive valyl-tRNA synthetase. Starvation was obtained following transfer to the cells to non-permissive temperature. Ribosomal proteins were obtained by treatment of either total lysates of freeze-thawed lysozyme spheroplasts or ammonium sulphate precipitate of ribosomes, with acetic acid. Differential labelling of the ribosomal proteins was observed in both strains: proteins from the rel+ strain appear more labelled than those from the rel- strain, the rate of labelling of individual proteins being about the same in both strains. Moreover ribosomal proteins were found as stable during starvation as total protein. It is thus concluded that in starving cells individual ribosomal proteins are not synthesized at equal rates. This indicates that the synthesis of ribosomal proteins is not only under the control of the rel gene.

Amino Acids↗
PubMed1975

The ribosomal proteins of Drosophila melanogaster. V. Analysis by two-dimensional gel electrophoresis of the ribosomal proteins of the temperature-sensitive lethal allele of suppressor of forked, l(1) su(f)ts67g: a putative ribosomal protein mutant.

The possibility that the ribosomes of a temperature-sensitive lethal allele of suppressor of forked, l(1)su(f)ts67g, contain a mutated protein was studied by two-dimensional gel electrophoresis. The results from these analyses revealed no differences in the ribosomal proteins between the mutant and the wild-type strain Ks. It was found, however, that the transition from larval to adult ribosomal protein complement, which occurs mainly during the third instar in Käs, takes place during puparium formation in the mutant at 25 degrees C while it appears to be fatally delayed at 30 degrees C. Thus mutant larvae shifted up to 30 degrees C at 70 hours after oviposition failed to pupate, but reached the third instar and showed an adult ribosomal protein pattern after 4 days. Also, the ribosome content in these larvae was found to be significantly lower compared with late third instar larvae. It was furthermore found that larvae collected within 50 hours of transfer back to 25 degrees C, after a 5 day, 30 degrees C treatment, showed a reversion to a ribosomal protein pattern identical with that of Käs late third instar larvae. The results suggest that the biosynthesis of imaginal ribosomes in l(1)su(f)ts67g is seriously impaired at 30 degrees C and less so at 25 degrees C. Further studies are necessary, however, in order to understand the exact nature of this mutant, which may turn out to be a useful tool in studies on the biosynthesis of ribosomes in D. melanogaster.

Alleles↗
PubMed1979

Selective spin-labeling of the ribosomal proteins of 70S ribosomes from Escherichia coli.

We have used a series of N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl) maleimide spin labels of different length to label, covalently and selectively, the most reactive sulfhydryl groups of 70S ribosomal proteins of Escherichia coli. Under short periods of labeling (1--2 min), less than two spin labels per ribosome are incorporated and were shown to be distributed mainly on five ribosomal proteins in the following order: S18 greater than S21, L27 greater than S17, and S12. With a long period of labeling (3 h) up to 13 spin labels are attached to the ribosome, and protein S1 is the most labeled. The shape of the electron paramagnetic resonance (epr) signal shows two components with a predominance for the strongly immobilized orientation, and the percentage of these components in each spectra has been evaluated. When the distance between the nitroxide group and the maleimide-attaching group exceeds 6 A (1 A = 0.1 nm) the strongly immobilized orientation disappears. The effect of magnesium ions on these selectively spinlabeled ribosomes shows that the dissociation into subunits does not affect the epr signal, but more spin labels are incorporated into the subunits if labeling is performed under conditions of dissociation.

Bacterial Proteins↗
PubMed1979

Interaction of Escherichia coli ribosomal protein S1 with ribosomes.

The binding affinity of Escherichia coli ribosomal protein S1 for 30S ribosomal particles has been determined by a sucrose gradient band sedimentation technique; the association constant (K) for the binding of one S1 protein per active 30S ribosomal subunit is approximately 2 X 10(8) M-1. The involvement of the two polynucleotide binding sites of S1 protein (site I binding single-stranded DNA or RNA, and site II binding single-stranded RNA only) in the S1--ribosomal interaction have been examined by competition experiments with polynucleotides of known affinity for the two sites. We find that site I does not contribute to the interaction; site II binding appears to provide a major part of the binding free energy, presumably by interaction of S1 with the 16S rRNA of the 30S particle. The remaining binding free energy is probably derived from the interaction of S1 protein with other proteins of the 30S subunit. The affinity of S1 for 70S ribosomes is about the same as that for the 30S subunit; the affinity of S1 for 50S subunits is much less. Binding affinities and stoichiometries of S1 protein with "inactive" 30S ribosomal subunits have also been examined.

Binding, Competitive↗
PubMed1976

Genetic studies of the ribosomal proteins in Escherichia coli. IX. Mapping of the ribosomal proteins, S2 and S20, by intergeneric mating experiments between Serratia marcescens and Escherichia coli K12.

Episomes of E. coli K12, which cover thrleu region of the chromosome, were transferred to Serratia marcescens. Ribosomal proteins from these hybrid strains were analyzed with phosphocellulose column chromatography. Two E. coli 30S ribosomal proteins, S2 and S20, could be detected in the ribosome of the hybrid strain in addition to all ribosomal proteins of S. marcescens.

Chromatography, Ion Exchange↗
PubMed1976

Genetic studies of the ribosomal proteins in Escherichia coli. X. Mapping of the ribosomal proteins, L21 and S15, by intergeneric mating experiments between Serratia marcescens and Escherichia coli K12.

Episomes of E. coli, which cover argG but not the str region, were transferred to Serratia marcescens. Ribosomal proteins from these hybrid strains were analyzed with phospho-cellulose or carboxy-methyl-cellulose column chromatography. Two E. coli ribosomal proteins, L21 and S15, could be detected in the ribosome from the hybrid strains in addition to the ribosomal proteins of S. marcescens.

Bacterial Proteins↗
PubMed1977

In vivo incorporation of ribosomal proteins into HeLa cell ribosomal particles.

Using high salt-washed ribosomal subunits from HeLa cells we detect three ribosomal proteins from the small subunit and five ribosomal proteins from the large subunit that enter ribosomal particles in the absence of ribosome formation (actinomycin D-treated cells); in untreated cells, they enter the ribosomal particles quickly, while the rest of the ribosomal proteins are incorporated gradually. At least two of the large subunit actinomycin D-resistant ribosomal proteins seem to be absent in the 55 S nucleolar ribosomal precursor.

Carbon Radioisotopes↗