FIG. 4.

Hydrophobicity plot of PA2403 from PAO1 with codons predicted to be under positive selection superimposed. Four prominent hydrophobic regions (hydrophobicity > 2) likely represent transmembrane domains. Red asterisks represent individual codons predicted to be under positive selection, and asterisk size corresponds to posterior probability of positive selection. With one exception, all amino acids that are predicted to have been under positive selection fall between hydrophobic domains and likely reside on the same side of the membrane after protein folding. Hydrophobicity plots of PA2403 with sequence from pyoverdine type II and III genes give similar results.