Alignment of BB0324 and the BamD TPR domains. Amino acid alignments of the N-terminal TPR (tetratricopeptide repeat) domains of B. burgdorferi BB0324, N. meningitidis BamD, and E. coli BamD. Each protein is predicted to contain two 34-residue TPR domains (indicated above alignments), with the amino acid positions of the TPR regions labeled at both the N- and C-termini. Amino acids are shaded based on sequence similarity, with the darkest shade indicating residues that are conserved among all three aligned sequences. The conserved TPR consensus sequence contains an Ala at positions 8 and 20, as indicated by asterisks. Note that the B. burgdorferi and N. meningitidis BamD proteins have these highly conserved residues in their TPR 1 and 2 motifs.