Effect of nalidixic acid and novobiocin on pBR322 genetic expression in Escherichia coli minicells.
AUTOR(ES)
Gómez-Eichelmann, M C
RESUMO
The effects of two deoxyribonucleic acid (DNA) gyrase inhibitors, nalidixic acid and novobiocin, on the gene expression of plasmid pBR322 in Escherichia coli minicells were studied. Quantitative estimates of the synthesis of pBR322-coded polypeptides in novobiocin-treated minicells showed that the synthesis of a polypeptide of molecular weight of 34,000 (the tetracycline resistance protein) was reduced to 11 to 20% of control levels, whereas the amount of a polypeptide of 30,500 (the beta-lactamase precursor) was increased to as much as 200%. Nalidixic acid affected the synthesis of the tetracycline resistance protein similarly to novobiocin, although to a lesser extent. The effects of nalidixic acid were not observed in a nalidixic-resistant mutant; those induced by novobiocin were only partially suppressed in a novobiocin-resistant mutant. The synthesis of one of the inducible tetracycline-resistant proteins (34,000) coded by plasmid pSC101 was also reduced in nalidixic acid- and novobiocin-treated minicells. These results suggest that the gyrase inhibitors modified the interaction of ribonucleic acid polymerase with some promoters, either by decreasing the supercoiling density of plasmid DNA or by altering the association constant of the gyrase to specific DNA sites.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=216271Documentos Relacionados
- Recombination between bacteriophage lambda and plasmid pBR322 in Escherichia coli.
- Response to temperature shifts of expression of the amp gene on pBR322 in Escherichia coli K-12.
- Cooperativity in nucleosomes assembly on supercoiled pBR322 DNA.
- Maintenance of plasmids pBR322 and pUC8 in nonculturable Escherichia coli in the marine environment.
- Gyrase inhibitors increase the content of knotted DNA species of plasmid pBR322 in Escherichia coli.