[Characteristics of the expression of the Ap- and Tc-genes of plasmid origin in lambda vectors]

Expression of Ap and Tc genes of the plasmid origin in lambda vectors where the effect of lac promoter and PL phage promoter can be traced has been studied. The different orientation of Ap gene relative to strong promoters (lac and PL) permitted the beneficial arrangement of Ap gene for its optimum expression to be established. The interfering interaction of the two closely arranged strong promoters, Ap gene and lac promoter, has been detected. This repressed considerably the expression of Ap gene. The enhanced expression of this gene has been observed under the effect of the removed PL phage promoter. The active expression of Tc gene has been only observed in clones with the recombinant lambda-pcv-20 molecule (without lac promoter), irrespective of the plasmid pcv-20 orientation. This, presumably, can be accounted for by the favourable secondary structure of the m-RNA of Tc gene providing the efficient translation.