The Pho3 Acid Phosphatase of Saccharomyces cerevisiae Cell Wall Hydrolyzes Inorganic Polyphosphates

Abstract While inorganic polyphosphate is an important component of the yeast cell wall, its metabolism in this compartment remains poorly understood. This study demonstrates that the whole cells and cell wall preparations of S. cerevisiae hydrolyze several substrates at acidic pH with release of phosphate: p-nitrophenyl phosphate, pyrophosphate, ATP, and glycerophosphate, exhibiting similar substrate affinities, as well as inorganic polyphosphates of 15 to 188 phosphate residues in the polymer chain. Magnesium ion is not required for this activity. Cell walls of the ∆pho3 mutant, which lacks the corresponding acid phosphatase, lacked this activity, while the activity was lower in the cell walls of the ∆bgl2 mutant. The obtained data indicate that the Pho3 acid phosphatase associated with the cell walls of S. cerevisiae is capable of hydrolyzing inorganic polyphosphate and, possibly, is involved in the control of its content in the cell wall.