The recombinant exopolyphosphatase PPX1 with a specific activity of ~300 U/mg protein was purified from the strain of Saccharomyces cerevisiae with the inactivated PPN1 gene transformed by the expression vector carryi...The recombinant exopolyphosphatase PPX1 with a specific activity of ~300 U/mg protein was purified from the strain of Saccharomyces cerevisiae with the inactivated PPN1 gene transformed by the expression vector carrying the yeast PPX1 gene. The recombinant PPX1 was similar to the PPX1 of wild strains in its substrate specificity and requirement for cations. PPX1 had the high substrate specificity to polyphosphates. The preparation was suitable for polyphosphate assay in the presence of orthophosphate and nucleoside phosphates not hydrolyzed by PPX1. The yield of the enzyme preparation was 250 assays per 1 g of the biomass. The recombinant PPX1 was successfully used in polyphosphate assay in different yeast species and some foodstuffs.展开更多
The Saccharomyces cerevisiae polyphosphatase PPN1 (uniprot/Q04119) degrades inorganic polyphosphates both by cleaving Pi from the chain end and by fragmenting long-chain polymers into shorter ones. In this study, we h...The Saccharomyces cerevisiae polyphosphatase PPN1 (uniprot/Q04119) degrades inorganic polyphosphates both by cleaving Pi from the chain end and by fragmenting long-chain polymers into shorter ones. In this study, we have found a new activity of this protein: it releases phosphate from dATP. The dATP phosphohydrolase activity of pure PPN1 was ~7-fold lower compared to the exopolyphosphatase activity. This activity was strongly stimulated by Co<sup>2+</sup> ions, as well as by ammonium ions, and inhibited by heparin and pyrophosphate similar to the exopolyphosphatase activity of PPN1. The Km value for dATP was 0.88 ± 0.14 mM. The dATP phosphohydrolase activity in the cells of PPN1-overexpressing yeast strain was several-fold higher than that in the parent strain. The other exopolyphosphatase of S. cerevisiae, PPX1, did not split Pi from dATP.展开更多
Inorganic polyphosphate (PolyP), a bioactive polymer with multiple functions, plays a key role in biomineralizaion and phosphorus homeostasis in yeasts. After phosphate starvation, the cells of Saccharomyces cerevisia...Inorganic polyphosphate (PolyP), a bioactive polymer with multiple functions, plays a key role in biomineralizaion and phosphorus homeostasis in yeasts. After phosphate starvation, the cells of Saccharomyces cerevisiae restored their pool of PolyP during the first 30 min of incubation in the media containing phosphate and carbon sources. The cells of parent strain accumulated PolyP both in glucose and ethanol-containing media. In the medium with glucose, the strain with inactivated PPX1 and PPN1 genes (encoding two major yeast polyphosphatases) accumulated 2-fold more PolyP than the parent strain. The PolyP in the mutant cells had a greater average chain length compared to the parent strain. The strain with inactivated exopolyphosphatase genes РРХ1 and PPN1 was incapable of PolyP synthesis in the medium with ethanol. The in vivo staining of cells with DAPI show that in the cells of parent strain PolyP appeared first in cytoplasm and mitochondria under cultivation in glucose-containing medium and in cytoplasm and vacuoles in the medium with ethanol. In the ΔPPX1ΔPPN1double mutant PolyP accumulated in cytoplasm and vacuoles under cultivation in glucose-contained medium.展开更多
文摘The recombinant exopolyphosphatase PPX1 with a specific activity of ~300 U/mg protein was purified from the strain of Saccharomyces cerevisiae with the inactivated PPN1 gene transformed by the expression vector carrying the yeast PPX1 gene. The recombinant PPX1 was similar to the PPX1 of wild strains in its substrate specificity and requirement for cations. PPX1 had the high substrate specificity to polyphosphates. The preparation was suitable for polyphosphate assay in the presence of orthophosphate and nucleoside phosphates not hydrolyzed by PPX1. The yield of the enzyme preparation was 250 assays per 1 g of the biomass. The recombinant PPX1 was successfully used in polyphosphate assay in different yeast species and some foodstuffs.
文摘The Saccharomyces cerevisiae polyphosphatase PPN1 (uniprot/Q04119) degrades inorganic polyphosphates both by cleaving Pi from the chain end and by fragmenting long-chain polymers into shorter ones. In this study, we have found a new activity of this protein: it releases phosphate from dATP. The dATP phosphohydrolase activity of pure PPN1 was ~7-fold lower compared to the exopolyphosphatase activity. This activity was strongly stimulated by Co<sup>2+</sup> ions, as well as by ammonium ions, and inhibited by heparin and pyrophosphate similar to the exopolyphosphatase activity of PPN1. The Km value for dATP was 0.88 ± 0.14 mM. The dATP phosphohydrolase activity in the cells of PPN1-overexpressing yeast strain was several-fold higher than that in the parent strain. The other exopolyphosphatase of S. cerevisiae, PPX1, did not split Pi from dATP.
文摘Inorganic polyphosphate (PolyP), a bioactive polymer with multiple functions, plays a key role in biomineralizaion and phosphorus homeostasis in yeasts. After phosphate starvation, the cells of Saccharomyces cerevisiae restored their pool of PolyP during the first 30 min of incubation in the media containing phosphate and carbon sources. The cells of parent strain accumulated PolyP both in glucose and ethanol-containing media. In the medium with glucose, the strain with inactivated PPX1 and PPN1 genes (encoding two major yeast polyphosphatases) accumulated 2-fold more PolyP than the parent strain. The PolyP in the mutant cells had a greater average chain length compared to the parent strain. The strain with inactivated exopolyphosphatase genes РРХ1 and PPN1 was incapable of PolyP synthesis in the medium with ethanol. The in vivo staining of cells with DAPI show that in the cells of parent strain PolyP appeared first in cytoplasm and mitochondria under cultivation in glucose-containing medium and in cytoplasm and vacuoles in the medium with ethanol. In the ΔPPX1ΔPPN1double mutant PolyP accumulated in cytoplasm and vacuoles under cultivation in glucose-contained medium.
