EXPRESSION OF RAT-LIVER ADOHCY HYDROLASE IN A RHODOBACTER-CAPSULATUS AHCY MUTANT RESTORES PIGMENT FORMATION AND PHOTOSYNTHETIC GROWTH

An amino acid alignment of fourteen S-adenosylhomocysteine hydrolases shows that sequences from six photosynthetic species and one species p ossibly derived from algae have an internal 36 to 41 amino acid sequen ce that is not present in hydrolase sequences from seven nonphotosynth etic species. In the photosynthetic eubacterium Rhodobacter capsulatus , the StLB1 strain has a disrupted hydrolase gene, and hydrolase activ ity is not detectable. Photopigment synthesis and photosynthetic growt h are significantly reduced in the StLB1 strain. Introduction of rat h ydrolase cDNA into the StLB1 strain restored hydrolase activity, photo pigment synthesis and photosynthetic growth. The results show that the 36 amino acid sequence of Rhodobacter capsulatus S-adenosylhomocystei ne hydrolase does not have a photosynthesis specific function. (C) 199 5 Academic Press, Inc..