FIG. 5.

Phylogenetic relationships of nifH sequences within the pseudo nif group, probably functioning in some process other than nitrogen fixation. The tree was constructed by the neighbor-joining method based on 118-amino-acid alignment positions corresponding to positions 45 to 153 of the K. pneumoniae nifH protein. Bootstrap values above 50 from 100 resamplings are shown for each node. Two chlorophyll iron protein sequences, that of Rhodobacter capsulatus bchL and that of Plectonema boryanum frxC, were used as outgroups. The scale bar shows 0.20 substitutions per site. Four clusters (I, II, III, and IV) consisting of sequences from termites are indicated. Numbers in parentheses denote numbers of clones having identical amino acid sequences from a single termite species (clones with unique sequences are not shown).