The evolution of microsporidian nucleotide transport proteins is characterized by an initial horizontal acquisition of a single gene followed by lineage-specific gene duplications.

<p>A phylogeny of NTT proteins for the microsporidian/<i>Rozella</i> clade of endoparasitic fungi and representative bacterial intracellular pathogens including <i>Chlamydia</i> and <i>Rickettsia</i>. The tree suggests a single common origin for NTT proteins in <i>Rozella</i> and microsporidians followed by the lineage- and clade-specific gene duplications that define microsporidian NTT protein evolution. The different clades of microsporidians were defined previously <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004547#ppat.1004547-Vossbrinck1" target="_blank">[26]</a>. A similar pattern of repeated gene duplication is evident in the tree for bacterial proteins. Values at nodes are Bayesian posterior probabilities.