The solubilization of ribosomal protein from Escherichia coli

The protein of Escherichia coli ribosomes has been prepared by allowingthe ribosomal RNAase to digest the ribosomal RNA under dialysis against various salts and buffers. The solubility of the protein was found to depend on the kind of salt present and on the pH, ionic strength, and temperature of the medium. At neutral pH's the solubility increased with increasing ionic strength, and complete solubilization of up to 17 mg/ml of ribosomal protein was attained in 1 M Tris buffer (pH 7.4).     

Similar organization of beta,beta'-subunit RNA-polymerase genes and adjacent ribosomal protein genes in Enterobacteriaceae and Pseudomonas putida

The genes coding for the RNA-polymerase beta,beta'-subunits and adjacent ribosomal protein genes in Escherichia coli, Salmonella typhimurium, Shigella flexneri, Serratia marcescens, Proteus mirabilis and Pseudomonas putida are compared by the Southern hybridization procedure. In all the species studied close clustering of the genes rplKAJL and rpoBC is demonstrated. Preliminary physical maps for these genes in S. typhimurium, S. flexneri, S. marcescens and P. mirabilis are proposed. Rifampicin is shown to stimulate the beta,beta'-subunit synthesis in all the species studied, suggesting the existence of attenuators localized in front of the rpoBC genes. The similar arrangement of the genes rplKAJLrpoBC in a number of bacterial species is proposed to be due to common mechanisms of their coordinate expression.     

Transcription of ribosomal protein genes carried on F'' plasmids of Escherichia coli.

Summary Spontaneous mutants of the petite-negative yeast Kluyveromyces lactis, resistant to the antibiotics chloramphenicol and oligomycin, were isolated and genetically characterized.Three chloramphenicol-resistant mutants showed non-Mendelian inheritance when crossed to sensitive parents.Of 5 oligomycin-resistant strains studied, three exhibited resistance due to the presence of an extrachromosomal mutation. The resistance of the other two deriving from a nuclear and recessive mutation.When two factor crosses in trans configuration were performed between two of the chloramphenicol and the five oligomycin-resistant mutants a polarity in recombination was observed with a predominance of sensitive (O^SC^S) over resistant (O^RC^R) reciprocal recombinants.Allelism tests carried out among the oligomycin-resistant mutants indicated the presence of at least two distinct extrachromosomal regions responsible for the resistance.     

Expression of Escherichia coli ribosomal protein and RNA polymerase genes cloned on plasmids.

Summary Fragments of drif ^d 18 DNA with different end-points within the set of structural genes of ribosomal proteins L11 (rplK), L1 (rplA), L10 (rplJ) and L12 (rplL) as well as the (rpoB) and (rpoC) subunits of RNA polymerase have been cloned on plasmids. These plasmids were transformed in host cells which were mutant for each of the genes, enabling expression of both wild-type (plasmid-borne) and mutant (chromosomal) genes to be differentiated. On the basis of these results we propose the following genetic structure for the region: rplK and rplA are in one operon; rplL, rpoB and rpoC are in a second. Our data suggest the possibility that rplJ is by itself in an operon situated between the other two.