FIG 9 .

Distribution of genes encoding key type II-secreted proteins within the Legionella genus. Gain and loss events pertaining to genes encoding type II-secreted NttD, LapA, LapB, PlaC, and ProA were modeled on a maximum-likelihood tree of 41 Legionella species, which was constructed based on the protein sequence encoded by 78 nearly universal genes (9). Colored circles and arrows indicate a gene gain event (upward-pointing arrow) or loss event (downward-pointing arrow) based on maximum parsimony, and colored cells (right) indicate the presence of nttD, lapA, lapB, plaC, and proA within a given species.