[C1 and cro repressors of lambda phages. Isolation of strains of bacteriophage lambda imm434 superproducing repressor cro].

A collection of recombinant plasmids directing the increased synthesis of the cro-repressor of lambda imm434 bacteriophage under control of the lacZ promoter of Escherichia coli has been constructed. About 87 000 molecules of cro-repressor monomer per cell, e. g. 0,7% of total cell protein are synthesized by the overproducers. Strain bearing one of such plasmids--pBS71-1. Several recombinant plasmids in which the cro-gene is placed under the control of early genes promoter of lambda phage (pl, pr, prm) have been also prepared. Plasmid pIL206, constructed on the basis of pIL203 vector, was used as a source of lambda-promoters.