[Effect of aminoglycosides on the binding of C14-benzylpenicillin by penicillin-binding proteins in Escherichia coli].

It was shown that preincubation of E. coli intact cells with gentamicin and streptomycin induced a marked increase in binding of 14C-benzylpenicillin to its final targets in the membrane i.e. penicillin-binding proteins (PBP). The stimulating effect of the aminoglycosides was also confirmed in experiments with a membrane fraction isolated from the cells preincubated with the aminoglycosides. The PBPs of the cells preincubated with the aminoglycosides were studied with SDS-PAAG electrophoresis. It was revealed that under the action of the aminoglycosides the quantity of the labeled substance (intensity of the bands on the fluorograms) fixed by the low molecular PBPs i.e. D-alanine carboxypeptidases increased. Moreover, the composition of the high molecular less mobile PBPs (transpeptidases) changed. The data are discussed in regard to the peculiarities of the effect of the aminoglycosides on the cells (bactericidal action, membrane tropism). The effect of the aminoglycosides can influence (along with the others) the results of their combined use with beta-lactams.