Point mutations in the different domains of the Saccharomyces cerevisiae plasma membrane PMA1 ATPase cause redistribution among fractions of inorganic polyphosphates.

Both ATP and inorganic polyphosphates (PolyP) appeared to be involved in the yeast energy homeostasis, in which plasma membrane PMA1 H+-АТРase plays one of the key roles. During biogenesis and functioning, the enzyme undergoes structural and regulatory phosphorylation. Aim of the work was to elucidate interconnection between functioning of the yeast PMA1 H+-АТРase carrying point substitutions that affected the enzyme structure-function relationship and its ability to be phosphorylated and PolyP metabolism. Effect of such replacements of phosphorylable and non-phosphorylable residues in three topologically and functionally different domains of the enzyme - membrane, extracytosolic, and C-terminal - on the metabolism of polyphosphates and distribution between short-, mid-, and long-chained PolyP fractions (PolyP1-PolyP4-5) has been studied. АТРase activity of membrane and most extracytosolic strains was noticeably lower comparing to the wild type. Of these mutants, three substitutions (L801A, E803A, E847A) have not caused significant changes in PolyP content regardless up to twofold drop of the ATPase activity; F796A with four-fold decreased activity has led to noticeable increase of mid-chained PolyP fractions. The most pronounced effect of PolyP redistribution was caused either by removal of potential (S846A, T850A, D851A) or established (S911A) phosphosites in the PMA1 ATPase or by altering type of the established phosphosite (S911D, T912D). Patterns of PolyP fractions for these two groups have significantly differed from each other, occurring in opposite directions for mutants with removed and changed phosphosite. Changing residue of phosphosite without altering its type (T850S) has not led to significant changes in PolyP content.Communicated by Ramaswamy H. Sarma.