Ribosomal proteins

Summary The ribosomal proteins fromE. coli strains B, C, K12 (A19), and MRE600 were extracted and analyzed by two-dimensional polyacrylamide gel electrophoresis. All four strains were found to be indistinguishable in their 50S ribosomal protein components, while there were differences among the 30S proteins. Strains K and B differ in protein S5 and S7. Strain C differs from strain B in protein S5 and from strain K in protein S7. MRE600 appears to be identical to strain C in respect to its ribosomal protein pattern. It was furthermore found that proteins S7 from strain K and B differ extensively in respect to size, charge, amino acid composition and immunological properties. The rather remote relationship between these two analogous proteins is quite remarkable when contrasted with the striking similarity in all but one of the other 30S and 50S proteins of the strains.Dedicated to the 65th birthday of Prof. G. Melchers.     

Ribosomal proteins

Summary A comparison of the protein patterns of the 70S and 80S ribosomes from various plants, E. coli and yeast by disc-gel electrophoresis has shown the following relations: 1. There is a greater similarity between chloroplast ribosomes from various plants than between chloroplast and cytoplasmic ribosomes obtained from the same plant. 2. The protein patterns of the cytoplasmic ribosomes from bean, spinach and tobacco are more similar to each other than when compared to that of wheat germ. 3. At least one band is common to cytoplasmic ribosomes from all plants tested. 4. Only very few bands with identical mobilities are observed between chloroplast and E. coli ribosomes and between cytoplasmic plant and yeast ribosomes.     

Ribosomal Antibiotics

In spite of decades of research, our understanding of the principles of antibiotic binding to the ribosome and the mechanisms of drug action remains only fragmentary. Recent progress in biochemical and genetic studies of some old and new antibiotics and the availability of high-resolution structures of the ribosome subunits allows mapping the antibiotic-binding sites at atomic resolution. In this review, interaction of three groups of antibiotics with the ribosome and the mechanisms of the drug action are discussed, considering the data used to map the binding sites of the new macrolide derivatives, ketolides, a novel clinically important antibiotic linezolid, and a still experimental drug evernimicin.     

Ribosomal proteins

Summary Ribosomal proteins of E. coli and yeast were separated by gel filtration on dextran (Sephadex) and polyacrylamide (Bio-Gel) columns. Both gels revealed a valuable separation of the proteins. Finally only Bio-Gel columns were used, since their polyacrylamide matrix is more resistant to the applied organic acids.The wide distribution of the molecular weights for both the E. coli and yeast ribosomal proteins was confirmed. E. coli ribosomal proteins were separated into three main groups by a single chromatography on Bio-Gel P-10. The same was true for yeast ribosomal proteins. Rechromatography of these protein groups resulted in a further valuable resolution. The fractionated proteins are recovered without any loss and they are very useful for further purification by other procedures, especially on a large scale basis.     

Ribosomal proteins

Summary Ribosomal proteins fromE. coli mutant N421 which is a spontaneous revertant from streptomycin dependence to independence have been compared to those of the wild type by two-dimensional polyacrylamide gel electrophoresis and by four immunochemical methods. The only detectable difference is a change in protein S5. This finding suggests that reversion from streptomycin dependence to independence can be caused not only by a mutation in protein S4, as described earlier, but also in protein S5.     

Ribosomal proteins

Summary The number of specific binding sites for homogenous single ribosomal proteins on 16S E. coli ribosomal RNA was investigated. The capacity of each of the twenty-one 30S subunit proteins to bind to the RNA was estimated by two newly developed methods, namely immunoprecipitation and a polyacrylamide gel method. Five proteins, namely S4, S7, S8, S15 and S20 bound specifically. One, S17, bound nonspecifically. No binding of the other proteins was detected. The binding proteins bound simultaneously to the RNA, with stimulated binding of proteins S7 and S8. Evidence is provided for the similarity of the chemistry of the binding sites of the binding proteins in Escherichia coli and in Bacillus stearothermophilus ribosomes.     

Ribosomal proteins

Summary The proteins of E. coli ribosomes were separated by a specially developed type of preparative polyacrylamide gel electrophoresis and proteins corresponding to 16 of the separated bands have so far been isolated. The amino acid compositions and the tryptic peptide maps of these proteins show certain degree of similarity as well as distinct differences. Determination of molecular weights revealed a wide range: The lowest molecular weight was 9,000 and the highest 41,000 for the proteins so far studied.The similarities between various ribosomal proteins in their amino acid compositions and their peptide maps on one hand and the wide range in their molecular weights on the other hand can be explained by a hypothesis involving gene duplications.     

Ribosomal antibiotics

In spite of decades of research, our understanding of the principles of antibiotic binding to the ribosome and the mechanisms of drug action remains only fragmentary. Recent progress in biochemical and genetic studies of some "old" and new antibiotics and the availability of high-resolution structures of the ribosome subunits allows mapping the antibiotic-binding sites at atomic resolution. In this review, interaction of three groups of antibiotics with the ribosome and the mechanisms of the drug action are discussed, considering the data used to map the binding sites of the new macrolide derivatives, ketolides, a novel clinically important antibiotic linezolid, and a still experimental drug evernimicin.     

Structural Aspects of Ribosomal RNA Recognition by Ribosomal Proteins

This review is focused on the structural aspects of interaction between ribosomal proteins and ribosomal RNA in bacterial ribosomes and complexes of ribosomal proteins with specific fragments of ribosomal RNA. Special attention is given to the recognition of specific spatial architecture of the double-stranded ribosomal RNA by ribosomal proteins and to the role of unstructured protein regions in stabilization of distant ribosomal RNA segments.     

Ribosomal protein neighborhoods

Summary The principal objective of the present experiments is to demonstrate the use of antibodies, raised against individual ribosomal proteins, to identify the member proteins of complexes created by treating ribosomes with bifunctional reagents. First, we verified our previous report that S18 and S21 can be crosslinked by treating 30S subunits with phenylenedimaleimide. Then, we used antibodies to identify the members of a complex obtained by treating 30S subunits with dimethyladipimidate; these are S5 and S8. We tentatively conclude that S18 and S21 as well as S5 and S8 are near neighbors in the 30S ribosomal subunit.     

Ribosomal Discrimination of tRNAs

Mutations in two proteins of the 30S ribosomal subunit indicate that the ribosome provides a recognition screen for tRNAs before, or simultaneous with, their interaction with mRNA.