ClustalW-BOXSHADE multiple sequence alignment of N-terminal fragments of FhaB homologs from strain 2336 and comparison to HpmA of P . mirabilis and FHA of B . pertussis. GenBank accession numbers of protein sequences are as follows: [GenBank:HSM_1651] (fhaB) filamentous hemagglutinin outer membrane protein [GenBank:ACA31420]; [GenBank:HSM_0268], (fhaB) filamentous hemagglutinin outer membrane protein [GenBank:ACA31896]; [GenBank:PMI2057] (hpmA) hemolysin [GenBank:CAR44120]; [GenBank:BP1879] (fhaB) filamentous hemagglutinin/adhesin, [GenBank:CAE42162]; [GenBank:HSM_1489] (fhaB) cysteine protease domain-containing protein [GenBank:ACA31239]; and [GenBank:HSM_1090] (fhaB) filamentous hemagglutinin outer membrane protein [GenBank:ACA30807]. Homologous regions are box-shaded black (identical amino acid residues) and gray (conserved amino acid substitutions). Arrows point to arginine, asparagine, glutamic acid, methionine, and serine residues that are shown to be involved in FHA secretion. Regions that correspond to the secondary structural components of FHA and HpmA are marked with a plus sign. S1 (NXXL), S2 (NXXG), and S3 (CXXC) indicate motifs that may be involved in stabilization of the helical structure of FHA and/or HpmA. Numbers at the end of each sequence denote amino acid positions.