Alastair T. Matheson

Correlation between 30S ribosomal proteins of Bacillus stearothermophilus and Escherichia coli.

SummaryThe 30S ribosomal proteins from Bacillus stearothermophilus strains 799 and 10 were purified and correlated with those from E. coli by comparing their two-dimensional electrophoretic mobility, immunological cross-reaction, molecular weight, amino acid composition and partial amino acid sequence. A high degree of similarity was observed among the proteins from these taxonomically distant bacterial species.

Ion effects on protein-nucleic acid interactions: The disassembly of the 50-S ribosomal subunit from the halophilic bacterium, Halobacterium cutirubrum

The 50-S ribosomal subunits from the extreme halophilic bacterium, Halo-bacterium cutirubrum, stable structurally and functionally in concentrated salt solutions were subjected to ionic environments depleted in either K+ or Mg2+ or both. Under these conditions specific classes of proteins are released from the subunit along with the 5 S RNA. Two-dimensional electrophoretic analysis of the resultant split protein fractions indicate some mutually exclusive effects of specific ions on the binding of specific proteins to the 23 S RNA as well as on the retention of 5 S RNA within the ribosomal macrostructure.

Homologies in procaryotic ribosomal proteins: Alanine rich acidic proteins associated with polypeptide translocation

Abstract : Translocation of the growing peptide chain in the synthesis of proteins is mediated to some extent by certain novel acidic ribosomal proteins. These proteins, designated L7 and L12 in Escherichia coli, are localized on the 50 S ribosomal subunit and differ only in the acetylation state of the N-terminal serine. The isolation, chemical characterization and N-terminal sequence analysis of an L7-L12 equivalent from B. stearothermophilus is reported, and the structural features are compared with the E. coli polypeptides, a comparison that is of particular note in view of the considerable interest in the structure, function and evolution of the genetic translation apparatus.

Procaryotic ribosomal proteins: N‐terminal sequence homologies and structural correspondence of 30 S ribosomal proteins from Escherichia coli and Bacillus stearothermophilus

Abstract : In attempting to evidence the evolution and the structure--function relationships of the ribosome in procaryotes the authors have undertaken a comparative amino acid sequence analysis of ribosomal proteins from Escherichia coli, and Bacillus stearothermophilus and Halobacterium cutirubrum, organisms which differ substantially in their physiological tolerances and taxonomic relationships. Previous structural studies have indicated a high degree of homology in some of the 30 S ribosomal proteins from E. coli and B. stearothermophilus. Reported in this paper is a summary of results on the study of the amino terminal regions of 19 ribosomal proteins E. coli strain Q13 and 21 from B. stearothermophilus strain 10.

A possible role in protein synthesis for the ribosomal-bound aminopeptidase in Escherichia coli B☆

Abstract : During an extensive study on the substrate specificity of a ribosomal-bound aminopeptidase in E, coli B it became apparent that the peptidase showed a rather narrow substrate specificity of such a nature to suggest it might be involved in the selective removal of the methionyl group from newly synthesized proteins. Some of the pertinent data is summarized in the communication. (Author)

Specific ribonucleoprotein fragments from the 30-S ribosomal subunits of Halobacterium cutirubrum, escherichia coli and Bacillus stearothermophilus

Abstract Ribonucleoprotein sub-particles from the 30-S ribosomal subunits of Halobacterium cutirubrum, Escherichia coli and Bacillus stearothermophilus have been prepared by exposing the ribosomal particles to 3.5 M LiCl in the presence of 0.01 M EDTA. The sub-particles formed contained only a few proteins. The two proteins present in the E. coli ribonucleoprotein subparticle were S8 and S15, both assembly proteins. When these ribonucleoprotein sub-particles were treated with ribonuclease (A or T 1 ) and then fractionated on Bio-Gel P-60, well defined fragments were obtained. In two of the Bio-Gel fractions (B and C) the fragments contained both RNA and protein and were stable in CsCl. The nucleotide composition of these two fractions showed an enriched C + G content. The four proteins found in the ribonucleoprotein sub-particle from B. stearothermophilus were present in either Bio-Gel fraction B or C, not in both, and their location was determined by the ribonuclease used to degrade the sub-particle. This would suggest the proteins are bound to specific sites on the ribonucleoprotein sub-particle.

The interaction of Escherichia coli ribosomes with p-chloromercuribenzoate☆

Abstract 1. When ribosomes from early log-phase cultures of Escherichia coli were incubated with 0.5 mM p -chloromercuribenzoate (PCMB) (in 10 mM Tris buffer (pH 7.6) containing 10 mM Mg 2+ ), the 100-S dimers were completely dissociated into 70-S monomers. 2. The dissociation was not reversed by increased concentrations of Mg 2+ and/or spermine. It was reversed, however, by 2-mercaptoethanol. 3. Mild I 2 oxidation also resulted in 100-S dissociation. Other sulfhydryl reagents, N -ethylmaleimide, 5,5′-dithio-bis-(2-nitrobenzoic acid) and iodacetate, showed no effect. 4. Approximately 10 moles of PCMB were bound per ribosome prior to the onset of dissociation of the 100-S particles. When 20–25 PCMB molecules were bound per ribosome dissociation was almost complete. 5. Dissociation of 100-S ribosomes stems from the reaction of PCMB with sulfhydryl groups presumably in the ribosomal protein. 6. Incubation of untreated ribosomes with 2-mercaptoethanol resulted in an association of 70-S particles into the 100-S dimer, suggesting the relative concentration of the 100- and 70-S particles in vivo may be governed by sulfhydryl interactions.

The Evolution of the Archaebacterial Ribosome

Summary The general properties of the archaebacterial ribosomes and the data available on the structure of both the ribosomal proteins and ribosomal RNA from the 5S RNA-protein domain and the ribosome “A” protein domain clearly support the concept that the archae-bacteria are a phylogenetic group quite distinct from either eucaryotes or eubacteria. The studies also indicate that some, at least, of the ribosomal components in the nuclear-cytoplasm of eucaryotes arose from an archaebacterial source.

The properties of ribosomal proteins from a moderate halophile

The ribosomes from the extreme halophile Halobacterium cutirubrum are unusual in that their ribosomal proteins are acidic rather than basic as is the case with almost all bacterial ribosomes (Bayley, S.T. (1966) J. Mol. Biol. 15, 420-427). To determine whether the ribosomes of a moderate halophile show similar properties the ribosomal proteins from an unidentified moderate halophile, which grows over a wide range of NaCl concentrations (0.04-4.3 M), were compared to those of Escherichia coli and H. cutirubrum. The proteins are slightly more acidic than those of E. coli but much less acidic than those from the extreme halophile as judged by their mobility on polyacrylamide gels and their amino acid composition. The electrophoretic profile on polyacrylamide gels of the ribosomal proteins from the moderate halophile is similar whether the cells are grown in 0.5 M or 4.25 M NaCl.

Salt stabilization of a 5 S RNA—protein complex from an extreme halophile, Halobacterium Cutirubrum

We have recently isolated and characterized a 5 S RNA-protein complex (RNP) from the ribosomes of an extreme halophile Halobacterium cu tirubrum [l] . This complex contains two proteins, HL-13 and HL-19, which have been shown to be equivalent to Escherichia coli proteins EL1 8 and ELS, respectively [l] . The organism has a high internal salt concentration [2] , and accordingly the complex is, as expected, optimally stable in high salt concentrations (greater than 3 M KCl). However, the complex is not stable in salt concentrations less than about 1 M. We shall show here that the breakdown of the complex that is observed as the salt concentration is lowered is correlated with a loss of secondary structure in the binding proteins, rather than a simple charge repulsion between the nucleic acid phosphates and carboxylates of these highly acidic proteins.