FIG. 1.

The flp-tad-rcp gene cluster. (A) Genetic organization of the flp-tad-rcp (ORFs PA4297 to PA4306) gene cluster in P. aeruginosa. The P. aeruginosa (Pa) cluster is compared with the A. actinomycetemcomitans (Aa) cluster. Each arrow represents a gene (not to scale) and indicates the transcription orientation. The original nomenclature of the A. actinomycetemcomitans gene cluster is indicated above each gene and the homologous genes in the P. aeruginosa cluster have been named similarly. In the P. aeruginosa cluster, the original annotation number is also indicated underneath. The P. aeruginosa fppA gene is homologous to the A. actinomycetemcomitans orfB gene and encodes a prepilin peptidase. The PA4293 and PA4296 ORFs (hatched) encode a histidine kinase sensor, PprA, and a response regulator, PprB, respectively. (B) Part of the amino acid sequence of the P. aeruginosa Flp pilin (72 amino acids). The positively charged residues within the leader peptide (underlined with dotted line) are represented by italics. The conserved residues within the Flp family of pilins are boldace and in larger letters (G, −1; A, +1; E, +5; and Y, +6). The hydrophobic domain downstream from the FppA cleavage site (indicated by an arrow) is represented by bold letters. The peptide that was used for raising Flp antibody has been underlined.