ColE1 cloning of a ribosomal RNA promoter region from λrif^d18 by selection for lambda integration and excision functions

The expression of the ribosomal RNA gene carried by the lambda transducing phage λrif^d18 is shown to be subject to stringent amino acid control. λrif^d18 DNA was digested with endonuclease EcoRI and ligated to similarly restricted ColE1 plasmid DNA. Selection for expression of lambda integration and excision gene activity carried by the same DNA fragment results in cloning of the promoter proximal portion of the 16S ribosomal RNA gene. The resulting chimera expresses λ integration and excision functions as well as encoding the promoter proximal half of a 16S ribosomal RNA gene.