Fusion of the lac genes to the promotor for the cytidine deaminase gene of Escherichia coli K-12.

Phage Mu has been inserted into the structural gene for cytidine deaminase (cdd). By the use of phage lambda (lac, Mu) the promoter for the cdd gene has been fused to lacZ. In these strains lacZ expression is regulated by the cytR repressor protein and is therefore induced by cytidine. The fusion strains were used for the isolation of cddo mutants. Plaque forming lambda phages carrying the different cdd-lacZ fusions were isolated. Studies of the cdd-Mu strains showed that the cdd gene is transcribed clockwise with respect to the Escherichia coli map.