Discovery, Cloning, Expression, Purification, and Characterization of Phosphoglycolate Phosphatase from Staphylococcus aureus

Staphylococcus aureus is a major cause of hospital-acquired infections. The multi-drug resistant nature of certain S. aureus strains makes the discovery of new drug targets for S. aureus vital. A newly discovered virulence factor from S. aureus was described as an ortholog of NagD from E. coli, a member of the nitrophenyl phosphatase family of the HAD (Haloacid Dehalogenase) superfamily. This thesis will show that this virulence factor is not an ortholog of NagD UMPase from E. coli, but rather a phosphoglycolate phosphatase (PGPase). If phosphoglycolate accumulates in the cell, it will inhibit the glycolytic enzyme triose phosphate isomerase (TPI). In S. aureus, TPI also serves as an adhesion protein that can bind to host cells; phosphoglycolate would interfere with this adhesion process and thus make it harder for S. aureus to infect host cells. Thus, this S. aureus PGPase may act as a virulence factor by degrading the TPI inhibitor phosphoglycolate. We cloned the gene, expressed and purified the protein, and determined and characterized its activity. We have subcloned this PGPase into a His•Tag vector, purified the protein using nickel affinity and size exclusion chromatography, and characterized enzymatic activity, optimal conditions (substrate, pH, and metal usage), and kinetics