FIG. 5.

Phylogenetic tree based on about 140-amino-acid MxaF-homologous sequences constructed by using the neighbor-joining method. Bootstrap values (from 1,000 replications) are indicated. Cluster 1 groups only MxaF sequences with the following GenBank/EMBL accession numbers (the first letters of the genus and species are given in parentheses): M17339 (Pd), AB004097 (Hm), M22629 (Mo), M31108 (Me), AF220764 (Mn), U41040 (Mm), and AF184915 (Msp). Cluster 2 groups the rhizobial sequences (accession numbers given in Materials and Methods) together with XoxF from P. denitrificans (U34346) and MxaF′ from M. extorquens (U72662). MxaF from Bacillus sp. (M65004) was used as the root. The topology of the tree constructed with the full-length MxaF-homologous sequences (thus excluding the rhizobial sequences) is similar. (α), member of α-Proteobacteria; (β), member of β-Proteobacteria.