Partial amino acid sequence alignments of FauA with TonB-dependent bacterial siderophore receptor proteins of high similarity. (A) Multiple sequence alignments of the FauA C terminus with C termini of bacterial siderophore receptor proteins producing the six highest-scoring alignments with FauA in GenBank database searches (GenBank accession numbers: P. aeruginosa FpvA, U07359; P. putida PupA, P25184; E. coli FhuE, P16869; P. putida PupB, P38047; P. aeruginosa FptA, P42512; Pseudomonas sp. strain M114 PbuA, Q08017). With the exceptions of residues Q717 and Y734 of FauA and T812 of FpvA (boxed), all amino acid residues shown are consistent with the PROSITE database TonB-dependent receptor protein signature 2 (PROSITE PDOC00354) consensus pattern (B) shared by most members of the TonB-dependent receptor family.