Novel Tools to Study Polyphosphate Biology in S. cerevisiae (Yeast) and Mammalian Cells

Abstract

Polyphosphates (polyP) are long chains of phosphates residues linked via high-energy phosphoanhydride bonds. PolyP’s regulation and its functions have been studied in bacteria and in yeast, but the synthesis and degradation pathways of polyP in mammals are still unknown. This makes it challenging to study polyP biology in mammalian cells. In this thesis, the E. coli gene Polyphosphate kinase 1 (PPK1), which encodes for an enzyme that synthesizes polyP, was used as a tool to study polyP biology in both yeast and mammalian cells. Using yeast as a model organism, expression of EcPPK1 led to a decrease in alpha-synuclein toxicity. Additional evidence shows the usefulness of using yeast as a model organism to study polyP’s protective effect on alpha-synuclein toxicity. In mammalian cells, transfection of EcPPK1 allowed for the modulation of polyP concentration in the cell. This led to the identification of six human proteins that are able to be polyphosphorylated. Preliminary data from RNA sequencing also shows that polyP in HEK293T cells regulates gene expression. Overall, this work demonstrated that EcPPK1 is a useful tool to study polyP biology in yeast and mammals.