INCREASED EXPRESSION OF THE GENTAMICIN RESISTANCE GENE BY A TN3 SEQUENCE LOCATED AT THE UPSTREAM REGION

Recombinant plasmids designated as pCH1 and pCH21 were constructed to determine the influence of the bla sequence on the expression of the g entamicin resistance gene which is located downstream of Tn3. Minimal inhibitory concentration (MIC) test and Northern hybridization results with the constructed plasmids showed that the transcription of the ge ntamicin resistance gene was initiated from the promoter, located down stream from the PstI site within the bla gene, and the hybrid promoter created by IR sequences of Tn3. Although the read-through transcripti on from the bla promoter did not occur, the transcription of the bla g ene increased the expression of the gentamicin resistance gene.