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

The discovery of novel LPMO families with a new Hidden Markov model

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 EF‐Tu concentration on the expression of tufB. To this aim cells were transformed with multicopy plasmids carrying either tufA or tufB. The intracellular EF‐Tu 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 temperature‐sensitive 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 EF‐Tu 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 EF‐Tu 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, 207–210 (1979)] and a derivative (pTuBo, compare preceding paper in this journal) were used to study the expression of both chromosomal and plasmid‐borne tufB. Transformation with either plasmid raised the intracellular EF‐Tu concentration by 30–60% depending on the nutritional conditions. Suppression of tufB expression was observed when the intracellular level of EF‐Tu increased after transformation with all plasmids mentioned above. The results are in accord with the concept that EF‐Tu acts as an autogenous feedback inhibitor involved in the regulation of tufB.Microbial Biotechnolog

New approaches to achieve high level enzyme production in Streptomyces lividans

Microbial Biotechnolog