NUCLEOTIDE-SEQUENCES OF GENES-CODING FOR PHOTOSYNTHETIC REACTION CENTERS AND LIGHT-HARVESTING PROTEINS OF ACIDIPHILIUM-RUBRUM AND RELATED AEROBIC ACIDOPHILIC BACTERIA

The nucleotide sequences of the puf operons of the Zn-bacteriochloroph yll a (Zn-BChl a)-containing photosynthetic aerobic bacteria, Acidiphi lium rubrum and Acidiphilium angustum, were determined. The nucleotide sequences of the pufL and -M of Acidiphilium cryptum, Acidiphilium mu ltivorum, and Acidiphilium organovorum were also determined. The puf o perons of A. rubrum and A. angustum contained pufB, -A, -L, -M, and -C as seen in other purple bacteria with an unknown gene directly upstre am of pufB, Comparing the deduced amino acid sequences of the puf gene s of the Acidiphilium species with those of other purple bacteria show ed that His L168, which is highly conserved in other bacteria, is repl aced by a glutamic acid in the Acidiphilium species. The three-dimensi onal structures of the reaction centers of Blastochloris (Rhodopseudom onas) viridis and Rhodobacter sphaeroides suggest that this residue lo cates closely to a special pair of bacteriochlorophylls and may be inv olved in the stabilization and function of ''Zn-BChl a''. The relative content of charged amino acid residues in the L and M subunit is a li ttle lower in A. rubrum (10% of total) than in B. viridis (12%), and t he tendency is more pronounced in the cytochrome subunit: 12.5% in A. rubrum and 18.8% in B. viridis.