Cloning, Characterization, and Distribution of an mRNA Encoding a H⁺-ATPase α Subunit in the Mantle of Pearl Oyster, Pinctada fucata

Mitochondrial ATP synthase is responsible for the production of the majority of the cellular ATP, which is composed of two major units: F₀ and F₁. Although much is known about the active complex (5 subunits (αβγδε)), the role of the α subunit in the catalytic mechanism remains unclear, particularly in bivalve animals. This study first cloned and identified the full-length sequence of the mitochondrial H⁺-ATP synthase α subunit cDNA gene in Pinctada fucata using the reverse transcriptase polymerase chain reaction (RT-PCR) technique. The Pinctada fucata mitochondrial H⁺-ATP synthase α subunit contains 1991 nucleotides, with the translation start site at nt 48 (ATG) and the stop codon at nt 1660 (TAA), encoding a polypeptide 553 amino acids in length, which shares high similarity to that of other animals (81% identity to fruit fly, 82% to carp, and 83% to humans). Alignment analysis of the well-conserved amino acid domains in the ATPase α subunit, the α/β signal transduction domain, showed that two residues (Asp³⁵⁸ and Asn³⁵⁹) differ from any other ATP synthase α subunit. In situ hybridization analysis was used to reveal the wide-spread distribution of mitochondrial H⁺-ATP synthase in various tissues in Pinctada fucata. This work will help further research on pearl energy metabolism to increase the output and quality of pearls to more efficiently utilize our rich pearl oyster resources.