The cya locus of Escherichia coli K12: organization and gene products.

The cya gene region of Escherichia coli K12 has been cloned into plasmid pBR322. Detailed analysis of the locus, using in vitro recombination techniques as well as specific labelling of gene products has given information on the organization and products of the region. The cya gene is preceded by two DNA segments which behave as promoters of equivalent strength; a divergent, very strong, promoter is also present in the same control region. The former pair of promoters direct transcription of the cya gene which is expressed as a 95,000 dalton polypeptide; the latter promoter controls synthesis of a 40,000 dalton polypeptide. The cya gene product can complement a cya delta mutation when fully expressed or when expressed as a protein truncated at its carboxy terminal end.