Fig. 9.

Hypotheses for heme biosynthesis pathway loss and acquisition in Kinetoplastea. (i) Under Hypothesis 1, the heme pathway was lost early in Kinetoplastea evolution, after the split with Prokinetoplastina, and before the emergence of bodonids. Subsequently, Strigomonadinae, Leishmaniinae and Phytomonas spp. acquired FeCH genes several times from different sources, while the Leishmaniinae and Strigomonadinae group obtained CPOX and HemG from a proteobacterium, and Leishmaniinae gained UROS from a Bacteroidetes. Some organisms in the bodonids acquired an FeCH gene. (ii) Under Hypothesis 2, the heme pathway was lost separately in bodonids, Trypanosoma, and lost in part in Phytomonas spp., and Leishmaniinae/Strigomonadinae. Subsequently, Phytomonas spp., Leishmaniinae, Strigomonadinae replaced part of their heme metabolism by the lateral acquisition of enzymes from different sources