[Effectiveness of expression of the chloramphenicol acetyltransferase gene controlled by foreign regulatory regions in Escherichia coli cells. I. Construction of vectors for the cloning of transcription regulatory elements].

New plasmids pML2.1 and pML4 were constructed for cloning the transcription regulatory regions. In the pML2.1 the structural part of chloramphenicol acetyltransferase gene of the pBR325 is under control of the lacUV5-promotor. Because the unique BamH1 cleavage site is in the joint region, one may use it for cloning transcription termination regions and selecting recombinant clones with the AprCms phenotype. As for the pML4, the foreign fragment integration is carried directly before the structural part of cat-gene and it is expressed only if the promotor regions are present. The plasmids were sequenced and their restriction maps were established. Small molecular weight (about 2,0 MDa, AprCmr) or only Apr intact genes and convenient disposition of many unique cleavage sites by restriction endonucleases make these plasmids useful for different genetic engineering experiments.