Nucleotide sequence of putP, the proline carrier gene of Escherichia coli K12.

The nucleotide sequence of the putP gene coding for the proline carrier in Escherichia coli has been determined and the amino acid sequence of the proline carrier deduced from it. The proline carrier is predicted to consist of 502 amino acids, resulting in a molecular weight of 54,343. The predicted protein is very hydrophobic (70% nonpolar amino acids), and its hydropathy profile suggests that it is composed of 12 hydrophobic segments with a mean length of 24.4 residues/segment. If these segments are assumed to be alpha-helical, the mean length of each domain corresponds to the thickness of the hydrophobic core of the membrane. Potential promoter, catabolite gene activator protein (CAP) binding sites and several palindromic sequences, which might be regulatory regions by the putA gene product, were also found in the 5' flanking region of the postulated putP gene. A typical rho-independent transcription termination signal was found after the terminator codon of the putP gene.