(A) Amino acid alignment of YscY with Pcr4 of P. aeruginosa and with SycE and SycH. Boxed residues, sequence identity; shaded residues, related or similar residues; underlined sequence, region predicted to form an amphipathic helix; dashes within sequences, gaps introduced to optimize alignment. (B) Helical wheel representations (61) of the underlined regions of YscY, SycE, and SycH. Hydrophobic amino acid residues are boxed.