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Biomedical subjects

E Wahle

Publications and source records attributed to E Wahle.

40 records · Page 3Linked to original sources
PubMed1984

Gene expression in a temperature-sensitive gyrB mutant of Escherichia coli.

The effect of gyrase inactivation on gene expression was studied by examining the activities of different promoters in a temperature-sensitive gyrB mutant of Escherichia coli. The relative activities of promoters affected by cAMP-binding protein (CAP), e.g., the lac promoter, are not reduced by gyrase inactivation but can, on the contrary, be enhanced. This stimulation depends on the promoter location or its structure. The tnaA promoter is activated when located near the origin of replication, suggesting a differential effect of gyrase inactivation on various chromosomal domains. Only silent or mutant promoters such as the non-functional wild-type bgl or the lacIq can be activated. No differential effect of gyrase inactivation on the lambda pL and the trp promoters carried by the phage can be detected.

Bacterial Proteins↗
PubMed1981

Identification of gene products programmed by restriction endonuclease DNA fragments using an E. coli in vitro system.

DNA restriction enzyme fragments have been used to programme the synthesis of polypeptides in an in vitro system without apparent loss in fidelity compared with supercoiled templates. The system is extremely sensitive, less than 1 microgram of DNA can be used to direct the synthesis of 35S-labelled polypeptides of sufficiently high specific activity such that products can be identified by SDS-PAGE after a few hours autoradiography. The ability to analyse fragments can be used to readily assign specific proteins to small regions of the coding template, to identify cloned gene products distinct from those of the vector, and to identify cloned genes expressed from their own promoters. The in vitro system can be used successfully with bacterial DNA from other species and efficient extracts can be prepared from any E. coli K-12 strain, which should greatly facilitate the purification of factors controlling the expression of specific genes by complementation assay.

Cloning, Molecular↗
PubMed1980

Involvement of DNA gyrase in rRNA synthesis in vivo.

The effects of oxolinic acid and novobiocin, two known inhibitors of DNA gyrase, on in vivo transcription in E. coli were investigated. The drugs inhibit the incorporation of 3H-uridine into RNA. It is shown that the effect is due to a direct influence of DNA gyrase on transcription, independent of interference with replication. By the use of rifampicin and hybridization experiments it was found that treatment with intermediate concentrations of DNA gyrase inhibitors reduces the rate of rRNA synthesis to a smaller extent than the rate of total RNA synthesis. By following the completion of growing rRNA chains we have also obtained evidence indicating that the average rate of rRNA chain growth is decreased in cells treated with inhibitors of DNA gyrase.

DNA Topoisomerases, Type II↗