The Primary Structure of the Cl−-Translocating ATPase, b Subunit ofAcetabularia acetabulum,Which Belongs to the F-Type ATPase Family

The genes possibly encoding the b subunit (50 kDa) of the Cl−-translocating ATPase ofAcetabularia acetabulumwere cloned from total RNA and from poly(A)+RNA and sequenced. The deduced amino acid sequence of the open reading frame consisted of 478 amino acids and showed high similarity to the β subunit of chloroplast F1-ATPase. Gene fragments encoding the putative β subunit of chloroplast F1- (273 bp) and mitochondrial F1-ATPases (332 bp) were also cloned fromA. acetabulumand sequenced, respectively. The deduced amino acid sequence of the chloroplast F1-ATPase showed 92.5% identity to the primary structure of the b subunit of the Cl−-translocating ATPase, while the nucleotide sequences were 79.9% identical. The deduced amino acid sequence of the latter was 77.3% identical to that of the b subunit of the Cl−-translocating ATPase and the nucleotide sequences were 67.5% identical. By Northern analysis, these three β-like genes were demonstrated to be transcribed with different sizes of RNA species. A putative chloroplast F1-β fragment also hybridized with chloroplast DNA isolated from the organism.