Characterization of messenger RNA in protoplasts of Saccharomyces carlsbergensis

1. (1) The pulse-labeled RNA extracted from enriched polysomal fractions of Saccharomyces carlsbergensis has been characterized by sedimentation analysis, by the effect of actinomycin D on the observed sedimentation patterns, by its sensitivity to ribonuclease action and by determinations of its base composition. It is concluded that this pulse-labeled RNA shows many of the properties which in general are ascribed to messenger RNA. 2. (2) It is shown, that polysomes which are charged with nascent α-glucosidase can be precipitated rather specifically with the aid of a purified rabbit anti-α-glucosidase γ-globulin fraction and a purified anti-rabbit γ-globulin antiserum from the goat. 3. (3) The pulse-labeled RNA extracted from the precipitated polysomes charged with nascent α-glucosidase has a sucrose gradient sedimentation pattern which is quite distinct from that of the pulse-labeled RNA from the total polysomal fraction. 4. (4) From this pattern and from the patterns obtained in pulse-double-labeling experiments with maltose-induced and non-induced protoplasts, it is tentatively concluded that the messenger RNA coding for the inducible enzyme α-glucosidase has a sedimentation coefficient of about 28 S

The synthesis of bacteriophage ΦX174-neutralizing protein in a subcellular system obtained from the spleen of ΦX174 immunized rats

The microsomal fraction of rat spleen was isolated at varying lengths of time after the application of a “booster”-injection of bacteriophage ΦX174 to the animal. Together with the “pH 5-enzyme” fraction, which is obtained routinely from the 100 000 × g spleen-supernatant of non-immunized rats, it formed the subcellular system which was tested for its ability to synthesize ΦX174-neutralizing protein. In a large number of experiments an increase was found in the concentration of ΦX174-neutralizing protein upon incubation of the subcellular systems under suitable conditions. The results obtained strongly suggest that this increase is due, at least partly, to true synthesis of this protein, as it could be shown to be ATP-dependent, ribonuclease-, and puromycin-, sensitive and also dependent on the time of incubation of the subcellular system

Studies on protein synthesis by protoplasts of saccharomyces carlsbergensis III. Studies on the specificity and the mechanism of the action of ribonuclease on protein synthesis

In this paper, the experimental results are presented of a continued study on the specificity and the mechanism of the inhibition by ribonuclease of protein synthesis in protoplasts of Saccharomyces carlsbergensis. By comparing the effects of native pancreatic ribonuclease with those of heat-denatured enzyme and protamine, it is shown that at least part of the observed inhibition of protein synthesis has to be attributed to the enzymic action of ribonuclease. The enzyme was found to cause both a lysis of the protoplasts and an inhibition of protein synthesis. Mg2+ was found to abolish the lysing action of RNAase, whereas protein synthesis remained inhibited for 50–90%. From the data it is concluded that RNAase inhibits protein synthesis primarily by its action on the yeast cell membrane

Possible intermediates in the biosynthesis of proteins. I. Evidence for the presence of nucleotide-bound carboxyl-activated peptides in baker's yeast

1. 1. In this paper evidence is presented for the occurrence of dialysable nucleotide-bound carboxyl-activated peptide compounds in extracts of ether-CO2-frozen fresh pressed baker's yeast. 2. 2. Furthermore, some data are given indicating the presence of carboxyl-activated peptides in “80S” microsomal RNP particles of the same yeast. 3. 3. The possible relation of the activated peptide compounds to cytoplasmic protein synthesis is discussed

Studies on protein synthesis by protoplasts of Saccharomyces carlsbergensis II. Reversal of the RNase effect of protein synthesis by polymethacrylic acid

The ribonuclease inhibited protein synthesis and respiration of yeast protoplasts can be restored by the addition of several polyanionic compounds, among which polymethacrylic acid proved to be the most effective one. The results of preliminary experiments with the ultracentrifuge indicate a strong complex formation between ribonuclease and polymethacrylic acid under the applied experimental conditions. It is suggested that the reversal of ribonuclease action by polymethacrylic acid in vivo may be attributed to such complex formation between ribonuclease and polymethacrylic acid

Studies on protein synthesis by protoplasts of Saccharomyces carlsbergensis I. The effect of ribonuclease on protein synthesis

Ribonuclease was found to inhibit the protein synthesis in the naked yeast protoplast for nearly 100%. Even small concentrations (5 μg/ml) were found inhibitory. The cause of this inhibition can be attributed at least in part to a 90% inhibition of the respiration. Amino acid uptake was found to be inhibited for 75%, and glycolysis for 50%

Induction and catabolite repression of α-glucosidase synthesis in protoplasts of Saccharomyces carlsbergensis

1. 1. Kinetic data on the repression, the derepression and the induction of α-glucosidase synthesis in protoplasts of Saccharomyces carlsbergensis suggested that some site other than the stereospecific site for the induction by maltose was involved in the repression by glucose. 2. 2. A study of the effect of actinomycin D on the induced and noninduced (derepressed) synthesis of α-glucosidase showed that induction by maltose caused mRNA to be synthesized. The mRNA coding for α-glucosidase synthesized during the first 120 min of induction appeared to be stable under conditions of both repression and derepression. 3. 3. During the phase of synthesis in which translation occurred only via the mRNA, glucose strongly affected α-glucosidase synthesis. Maltose did not exert any effect on translation. 4. 4. When both transcription and translation occurred, glucose inhibited transcription. However, translation and transcription were not affected to the same extent by glucose