Beta-subunit of ATP-synthase: a useful marker for studying the phylogenetic relationship of eubacteria.

The genes encoding the beta-subunits of ATP-synthases (ATPases) from Bacteroides fragilis DSM 2151, Cytophaga lytica DSM 2039 and 'Taxeobacter ocellatus' were cloned. The nucleotide sequences were determined completely for the genes of the first two organisms and to a major part for that of 'T. ocellatus'. The predicted amino acid sequences were compared with previously published amino acid sequences of beta-subunits. Two characteristic insertions were found in genes from organisms belonging to the so-called bacteroides-cytophaga-flavo-bacterium group. The remaining structure shows a high degree of sequence similarity within this group. These data support the conclusions drawn from comparative 16S rRNA sequence analyses that organisms in this phenotypically heterogeneous group are phylogenetically related. A phylogenetic tree was constructed based on a distance matrix of optimally aligned amino acid sequences of beta-subunits of ATPases of various eubacteria, chloroplasts and mitochondria. It is in good agreement with a tree derived from 16S rRNA sequence analyses.