Abstract
Acetabularia acetabulum (A.a.) is a giant unicellular marine alga. We have demonstrated the presence of V-ATPase and V-PPase in the vacuole as observed for higher plants. Molecular cloning elucidated that the putative open reading frame of V-PPase may encode 721 or 751 amino acids. By heterologous expression of AcVP (A. a. V-PPase gene) in a yeast VMA3-deficient strain, analyses of the function and functional domains were conducted: 1) Expression of AcVP in the BJ5459 strain (wild type) demonstrated that the open reading frame encodes 751 amino acids. 2) As the results of expression of AcVP in a
VMA3-deficient strain, the acidification of yeast vacuoles was observed by fluorescence microscopy. 3) In pumpkin V-PPase, Glu-749 was reported to be modified with a DCCD analogue. We observed that the Glu-732 in A. a. V-PPase corresponding to the Glu-749 did not affect the proton pumping activity.
