FIGURE 4.

Distribution of terminal oxidases and various anaerobic traits shared between 20 bacteria and 10 eukaryotes in a selection of taxa representative of various lineages and metabolic combinations. The list of taxa includes representatives of the four categories of alphaproteobacteria that have been defined on the basis of the presence and oxygen affinity of terminal oxidases, as presented in the Section “Results and Discussion.” The taxa were selected from those listed in Supplementary Figure S1 to provide the broadest combinations of metabolic traits, which additionally included several traits of anaerobic metabolism that are shared with some eukaryotes (Atteia et al., 2013). The accession numbers for the key proteins that define each trait are listed in Supplementary Table S2; the distribution of ASCTI, malic enzyme, and fumarase (Müller et al., 2012) are not shown because they are widespread among the taxa considered (Supplementary Table S2) and to simplify the graph.