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

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.