Figure 2. Phylogeny of species used for multi-sequence alignment of NifD and NifK.

The species in the data analysis set (identifiers and species are in Table S1) were superimposed on a simplified whole-proteome tree from Jun et al. (Figure 2 in [34], constructed with whole proteomes of 884 prokaryotes). Identifiers are based upon the six nitrogenase groups; species with both Nif and either Anf or Vnf have more than one identifier.