Structural gene for the phosphate-repressible phosphate-binding protein of Escherichia coli has its own promoter: Complete nucleotide sequence of the phoS gene

The complete nucleotide sequence of the phoS gene, the structural gene for the phosphate-repressible, periplasmic phosphate-binding protein Escherichia coli K-12, was determined. The phosphate-binding protein is synthesized in a precursor form which includes an additional N-terminal segment containing 25 amino acid residues, with the general characteristics of a signal sequence. The amino acid sequence derived from the nucleotide sequence shows the mature protein to be composed of 321 amino acids with a calculated molecular weight of 34,427. The phoS gene is not part of an operon and is transcribed counterclockwise with respect to the E. coli genetic map. A promoter region has been identified on the basis of homology with the consensus sequence of other E. coli promoter regions. However, an alternative promoter region has been identified on the basis of homology with the promoter regions of the phoA and phoE genes, the structural genes for alkaline phosphatase and outer-membrane pore protein e, respectively.