[Effect of poly(dA).poly(dT) sequence inserted into EcoR1 site of pBr322 plasmid on the expression of tet and bla genes].

The 99 base pair poly(dA).poly(dT) stretch was inserted into EcoRI site of pBR plasmid. The effect of this insertion on tet-gene expression from P2 promoter, and bla-gene expression from P1 and P3 promoters was studied. The insertion results in a slight enhancement of the resistance of the cells to tetracycline and a decreased sensitivity to ampicillin. It is suggested that these findings reflect the effect of insertion on the transcription of the corresponding genes.