Fig. 1. Genetic organization of the P.aeruginosa tat gene cluster. The genetic organization of the P.aeruginosa tat genes is compared with that of E.coli. The percentage identity between the corresponding homologous Tat proteins is indicated. The tatD and tatE genes are not clustered with the other tat genes of P.aeruginosa and E.coli, respectively. In P.aeruginosa, the intergenic region between the tatA and tatB genes is 14 bp long, whereas the start codon of tatC overlaps with the stop codon of tatB. The stop codon of the gene (hisE) encoding a 111 amino acid protein homologous to the A.chroococcum phosphoribosyl ATP pyrophosphatase is located 26 bp upstream from the tatA start codon. The start codon of the gene encoding a 235 amino acid protein homologous to a hypothetical protein from A.haemolyticus overlaps with the stop codon of tatC. The deduced size in amino acids of the gene products is indicated above or under each gene for E.coli and P.aeruginosa, respectively.