Multiple-sequence alignment of FpvA and its homologues. Proteins related to FpvA were identified with BLAST (1) (http://www.ncbi.nlm.nih.gov/BLAST/), and the mature sequences (putative signal peptidase cleavage sites were identified by the method of Nielsen et al. [46] [http://www.cbs.dtu.dk/services/SignalP/]) were aligned with CLUSTALW (68) (http://www.ebi.ac.uk/clustalw/). Only the N termini are shown. FptA, P. aeruginosa Fe(III)-pyochelin receptor (accession number P42512); PbuA, P. putida M114 Fe(III)-pseudobactin M114 receptor (accession number Q08017); FhuE, E. coli receptor for Fe(III)-coprogen, -ferrioxamine B, and -rhodotorulic acid (accession number P16869); FauA, Bordetella pertussis Fe(III)-alcaligin receptor (accession number AAD26430); PupA, P. putida WCS358 Fe(III)-pseudobactin 358 receptor (accession number P25184); FpvA, P. aeruginosa Fe(III)-pyoverdine receptor (accession number P48632); PupB, P. putida WCS358 Fe(III)-pseudobactin BN7/BN8 receptor (accession number P38047); PA2466, probable P. aeruginosa TonB-dependent receptor (accession number D83337).