The azurin gene from Pseudomonas aeruginosa. Cloning and characterization

We have cloned and sequenced the Pseudomonas aeruginosa azurin structural gene and its flanking regions. The DNA sequence predicts a pre-protein with a signal peptide of 19 amino acids followed by the 128-amino-acid mature azurin protein. Nuclease-S1 mapping and primer elongation experiments indicated two 5' termini of the azurin transcript. The major transcript of the azurin gene is initiated around 35 base pairs upstream from the translational start. The minor transcript, with a promoter region sharing homology with a consensus nif promoter of Klebsiella pneumoniae and also with other Pseudomonas genes, is initiated 145 base pairs upstreams of the azurin initiation codon. Downstream from the azurin structural gene a sequence similar to a transcriptional terminator is found. Northern blot analysis indicated two sizes of the azurin mRNA (0.54 kb and 0.65 kb) confirming the S1 mapping and the predictions from the nucleotide sequence.