The primary structure of the Cl^--Translocating ATPase, b subunit of Acetabularia acetabulum, which belongs to the F-type ATpase family

The genes possibly encoding the b subunit (50 kDa) of the Cl - translocating ATPase of Acetabularia acetabulum were cloned from total RNA and from poly(A)¹ 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 from A. acetabulum and 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.