CustalW analysis of Gifsy-1 Xis and proteins containing proline loops. A residue ruler is indicated along the top of the figure and is numbered according to the Gifsy-1 Xis sequence. The residue number for individual proteins is indicated on the left-hand side of the figure. Residues aligned with the Gifsy-1 Xis H-T-H motif are included in the blue box A. Residues aligned with the Gifsy-1 Xis FPPP loop are included in the red box B. Residues aligned with the Gifsy-1 Xis β-sheet are included in the black box C. The secondary structures assigned to the Gifsy-1 Xis protein are aligned with the sequences along the top of the diagram. Red rectangles indicate α-helix sequences and yellow arrows indicate β-sheet structures, respectively. The proteins listed from top to bottom are as follows: Shigella flexneri Orf41, Shigella flexineri Rox, P4 Vis, Yersinia Pestis YPO1904, E. coli Z112, Salmonella Typhimurium Gifsy-1 Xis, phage lambda Xis, E. coli phage Phi80 Xis, phage e14 Xis, phage P21 Xis, CP4-57 ALPA.