102 research outputs found
Transfer of plasmid-borne tuf mutations to the chromosome as a genetic tool for studying the functioning of EF-TuA en EF-TuB in the E. coli cell
Microbial Biotechnolog
Translational frameshifts induced by mutant species of the polypeptide-chain elongation factur-tu of escherichia-coli
Microbial Biotechnolog
In vivo studies disprove an obligatory role of azurin in denitrification in Pseudomonas aeruginosa and show that azu expression is under control of RpoS and ANR
Microbial Biotechnolog
A revised bacterial polypeptide chain elongation cycle with a stepwise increase in restriction of unwanted ternary complexes by the ribosome
Metals in Catalysis, Biomimetics & Inorganic Material
Mutants of the elongation factor EF-Tu, a new class of nonsense suppressors
Microbial Biotechnolog
FIS-dependent trans-activation of tRNA and rRNA operons of Escherichia coli
Microbial Biotechnolog
Suppression of nodulation gene expression in bacteroids of Rhizobium leguminosarum biovar viciae
Microbial Biotechnolog
tuf Gene dosage effects on the intracellular concentration of EF-TuB
In this paper we have studied the effect of raising the intracellular EFâTu concentration on the expression of tufB. To this aim cells were transformed with multicopy plasmids carrying either tufA or tufB. The intracellular EFâTu concentrations were determined by the specific immunoelectrophoresis assay described in the preceding paper in this journal. We have cloned the tufA gene in a plasmid, containing the powerful major leftward promoter (Pl) of phage λ Transcription from Pl can be repressed at low temperature by a temperatureâsensitive repressor and acitvated by heat induction. Cloning occurred in two orientations in a single EcoRI site about 150 base pairs downstream of Pl. Cells carrying either plasmid were shown to contain an almost doubled amount of EFâTu at temperatures from 28°C to 37°C. This indicates that transcription of tufA can proceed from a possible binding site for RNA polymerase on these cloned fragments. The EFâTu level was further increased to about 30% of total cellular protein after a temperature shift from 37°C to 43°C. The multicopy plasmid pTuB1 described by Miyajimaet al. [FEBS Lett. 102, 207â210 (1979)] and a derivative (pTuBo, compare preceding paper in this journal) were used to study the expression of both chromosomal and plasmidâborne tufB. Transformation with either plasmid raised the intracellular EFâTu concentration by 30â60% depending on the nutritional conditions. Suppression of tufB expression was observed when the intracellular level of EFâTu increased after transformation with all plasmids mentioned above. The results are in accord with the concept that EFâTu acts as an autogenous feedback inhibitor involved in the regulation of tufB.Microbial Biotechnolog
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