Synthesis of ribosomal proteins during growth of Streptomyces coelicolor

Changes in expression of ribosomal protein genes during growth and stationary phase of Streptomyces coelicolor A3(2) in liquid medium were studied. Proteins being synthesized were pulse-labelled with [³⁵ S]-methionine, separated by two-dimensional poly-acrylamide gel electrophoresis, and quantified using the Bioimage computer software. Most of the ribosomal proteins were synthesized throughout the life cycle. Exceptions were two proteins whose synthesis drastically decreased at the approach of stationary phase. These two proteins were identified in purified ribosomes as homologues of Escherichia coli ribosomal proteins L10 and L7/L12, using antibodies raised against fusion proteins between these ribosomal proteins and Escherichia coliβ-galactosldase. The genes (rplJ and rplL) encoding the L10 and L7/L12 proteins were contained in a 1.2 kb BamHl fragment that was cloned and sequenced. The linkage and order of the genes coincide with other L10-L7/L12 operons. However, L11 and L1 genes were not present immediately upstream of the L10 gene, as is the case for E. coli and other bacteria. Instead, two open reading frames of unknown function were found immediately upstream of the L10 gene, in an adjacent 1.9 kb BamHl fragment.     

Synthesis of ribosomal proteins during the yeast cell cycle

The synthesis of ribosomal proteins during the cell division cycle of Saccharomyces cerevisiae has been examined. A technique was utilized whereby cells in unique phases of the cell cycle were selected from an asynchronous culture after the period of pulse labeling. Some of the proteins of the small and large ribosomal subunits were synthesized continuously throughout the cell cycle and there was no evidence of discontinuous synthesis for any of the ribosomal proteins.     

Synthesis of ribosomal proteins in merodiploid strains of Escherichia coli

Summary The regulation of the synthesis of r-proteins in Escherichia coli was investigated by increasing the dosage of the genes for a limited number of ribosomal proteins (r-proteins) using either transducing phage fus 3 (Lindahl et al. 1977) or rif ^d18 (Kirschbaum and Konrad 1973). During exponential growth the presence in the cell of either lysogenised transducing phage did not increase the rate of synthesis or degradation of any of the 31 r-proteins whose genes are duplicated. Experiments were also performed to determine whether r-protein synthesis during the period of unbalanced r-protein synthesis that follows nutritional enrichment was sensitive to an increase in gene dosage. Duplication of the 27 r-protein genes on fus 3 did not alter the rate of synthesis of any of the r-proteins after enrichment. However, gene dosage effects were detected for at least 3 of the r-proteins whose genes were duplicated of rif ^d18.     

Synthesis of individual ribosomal proteins in Escherichia coli B/r

The differential synthesis rates of individual ribosomal proteins (r-proteins) were measured in Escherichia coli B/r during the transition period following a nutritional shift-up from succinate minimal to glucose/ammo acids medium. These rates were observed to respond sequentially to the shift-up; the differential synthesis rate of protein L28 begins to increase within 0.1 of a minute following the shift-up, while the protein L29 synthesis rate begins to increase only after a lag of 2.5 minutes. The onset of induction of the remaining r-proteins occurs within this 2.5-minute interval. Furthermore, there was a twofold variation in the acceleration of the differential synthesis rates of individual r-proteins. Within the initial two to ten-minute period following the shift-up the differential synthesis rates of most r-proteins reached values ranging from 2.2 to 3.0-fold higher than the pre-shift rates, before declining to the post-shift steady-state values. It is suggested that the increases in the differential synthesis rates of r-proteins result in part from increases in the translational efficiency of messenger RNA in the post-shift growth medium and in part from increases in the amount of r-protein mRNA that is present.     

Synthesis and conservation of ribosomal proteins during compensatory renal hypertrophy.

The rate of synthesis of ribosomal proteins was investigated as an index of the rate of production of ribosomes in mouse kidney during the first few days after contralateral nephrectomy. Compensatory renal hypertrophy was not associated with a major increase in the synthetic rate of ribosomal proteins and rRNA. Instead, the ratio of the rate of ribosomal-protein synthesis to that of total protein synthesis remained nearly constant. The conformation of glutaraldehyde-fixed ribosomes and ribosomal subunits was unchanged. During the early stages of compensatory renal hypertrophy the accretion of rRNA is due largely to conservation of ribosomes that would otherwise have been degraded.     

Yeast ribosomal proteins

Summary Homology maps between bacteriophages 81, 80 and were constructed on the basis of electron microscope observation of DNA heteroduplexes. In 81/80 heteroduplex, the left half and the right terminal region of 13% the total molecular length were highly homologous, while the remaining region covering the early gene cluster was entirely nonhomologous. In 81/ heteroduplex, high-degree homologies were detected at the left 14% terminal region covering the head gene cluster, the central 3.8% region covering the att-int-xis region and the 1.3% Q homology region. Low-degree homologies of shorter length were scattered at the tail gene cluster, b2 region, cIII region, PQ region and SR region. Comparing our results with the homology maps of other lambdoid phages reported by Simon et al. (1971) and Fiandt et al. (1971), a phylogenic relation of 81 to other lambdoid phages and the role of recombination in the course of divergence of lambdoid phages are discussed.     

Yeast ribosomal proteins: VII. Cytoplasmic ribosomal proteins from Schizosaccharomyces pombe

The cytoplasmic ribosomal proteins from a fission yeast Schizosaccharomyces pombe were analysed by two-dimensional polyacrylamide gel electrophoresis. Seventy-three protein species were identified in the 80S ribosome, and named SP-S1 to SP-S33 and SP-L1 to SP-L40 in the small and large subunits, respectively. Many of these proteins could be correlated to those of Saccharomyces cerevisiae on the basis of their electrophoretic mobilities. Eleven proteins were isolated from the 80S ribosome, and their amino acid compositions were determined. Of these, SP-S6, SP-L1, SP-L12, SP-L15, SP-L17, SP-L27, SP-L36 and SP-L40c and d were sequenced from their amino-termini. SP-S28 and SP-L2 appear to have their amino-termini blocked. These results were compared with the data available for the S. cerevisiae and rat liver ribosomal proteins. The S. cerevisiae counterparts of the eight proteins mentioned above were found to be YS4, YL1, YL10, YL14, YL35, YL40 and YL44c and d, respectively. The rat liver counterparts of SP-S6, SP-L1, SP-L27 and SP-L40c and d were the rat S6, L4, L37 and P2, respectively. Comparison of the partial sequences of these ribosomal proteins suggests that these two yeasts are relatively far apart, phylogenetically.