Figure 2.

Phylogenetic tree of the 24 kDa-like module of the hydrogenase of N. ovalis, mitochondrial complex I 24 kDa subunits, bacterial NuoE, and bacterial hydrogenase subunits. See methods for the Accession Numbers and how the tree was calculated. H: N. ovalis hydrogenase, M: ciliate mitochondrial. Bootstraps are only indicated in the tree if they are ≥ 50. Box 1 marks 24 kDa modules that are fused with their corresponding 51 kDa modules (with the exception of Nitrosospira multiformis). All bacteria in this box (with the exception of Nitrosospira multiformis) have a [NiFe] hydrogenase. The mitochondrial/alpha-proteobacterial 24 kDa modules are not fused with their 51 kDa counterparts (Box 2).