Regulation of diaminopimelate decarboxylase synthesis in Escherichia coli. II. Nucleotide sequence of the lysA gene and its regulatory region.

The complete nucleotide sequence of the lysA gene and its regulatory region was determined. At the 3' end of the lysA gene an open reading frame was revealed in the opposite direction and was identified as the galR coding region. Only six base-pairs are present between the two translational stops and thus both transcription units are overlapping in vivo. Translational gene fusions constructed in vitro with the beta-galactosidase gene were used to identify the lysA initiating ATG. The sequence encodes a 420 amino acid long peptide for a predicted molecular weight of 46,099. No attenuation-like sequence was found at the beginning of the lysA gene. A target of the LysR activator protein was localized on a 73 base-pair fragment found 48 base-pairs upstream from the lysA coding region. The presence of this DNA sequence on a multicopy plasmid led to a net decrease of lysA expression, indicating limiting amounts of active LysR protein in the cytoplasm.