Effects of plasmid pBR322 on respiratory and ATPase activities in Escherichia coli.

The effects of antibiotic resistance plasmids on respiratory and ATPase activities were investigated in Escherichia coli. The rates of oxygen consumption coupled to the oxidation of succinate and NADH, ATP hydrolysis, and ATP-Pi exchange were measured in isolated membrane vesicles prepared from HB101 strains that contained derivatives of plasmid pBR322. The rates of oxygen consumption coupled to the oxidation of NADH were independent of the presence or absence of plasmids in the strains from which the vesicles were prepared. In contrast, the mean rates of oxygen consumption coupled to the oxidation of succinate, ATP hydrolysis, and ATP-Pi exchange were 140-292% higher in vesicles made from plasmid-containing strains than from plasmid-free HB101 and independent of the expression of the plasmid-encoded tetracycline/H+ antiporter.