Fig. 6.

Altered selection pressure in Latin American BabA. a Alignment showing Ka/Ks ratio over a region of the BabA protein sequence corresponding to amino acid 183-265 of the ELS37 BabA showing the ELS37 BabA sequence on top and the consensus sequence from the multiple alignment of Nicaraguan BabA proteins at the bottom. Amino acids in red letters are identical in all the isolates and those with blue letters are shared in 90 % of the isolates. Cyan-shaded cysteine residues are predicted to form disulphide bonds constraining the helices of the binding domain inferred from homology to the SabA sequence [62]. Under the ELS37 sequence the Selecton results are shown, the upper line when calculating Ka/Ks based on all complete sequences plus the Nicaraguan sequences and the lower line when basing the Ka/Ks ratio only on the Latin American complete sequences and the Nicaraguan ones. Residues under no selection are white while residues under purifying selection are shown in red and those under positive selection are shown in shades of green. b PhyML tree based only on the residues corresponding to those of the alignment in (a) of the same 170 BabA protein sequences as in Fig. 4. Nicaraguan isolates are shown in red, urban Latin American isolates are shown in blue, North American isolates in black, African isolates in green and European isolates in purple, EastAsian isolates in brown, other Asian isolates in yellow and Amerindian isolates in orange