PHYLOGENETIC ANALYSIS OF PHOTOSYNTHETIC GENES OF RHODOCYCLUS-GELATINOSUS - POSSIBILITY OF HORIZONTAL GENE-TRANSFER IN PURPLE BACTERIA

Nucleotide sequences of the genes coding for the M and cytochrome subu nits of the photosynthetic reaction center of Rhodocyclus gelatinosus, a purple bacterium in the beta subdivision, were determined. The dedu ced amino acid sequences of these proteins were compared with those of other photosynthetic bacteria. Based on the homology of these two pho tosynthetic proteins, Rc. gelatinosus was placed in the alpha subdivis ion of purple bacteria, which disagrees with the phylogenetic trees ba sed on 16S rRNA and soluble cytochrome c2. Horizontal transfer of the genes which code for the photosynthetic apparatus in purple bacteria c an be postulated if the phylogenetic trees based on 16S rRNA and solub le cytochrome c2 reflect the real history of purple bacteria.