Multiple alignment of the amino acid sequence of NorM with those of representative homologs in Vibrio parahaemolyticus (Vp), Vibrio cholerae (Vc), Neisseria meningitidis (Nm), and Escherichia coli (Ec), using CLUSTAL W. *, identical residues; :, >60% homologous residues. The conserved regions G184KFGXP189 and L381RGYKD386 are overlined.