title: Nuclear exopolyphosphatase of Saccharomyces cerevisiae is not encoded by the PPX1 gene encoding the major yeast exopolyphosphatase.
abstract: Intact nuclei from a parental strain CRY and a PPX1-mutant CRX of Saccharomyces cerevisiae were isolated and found to be essentially free of cytoplasmic, mitochondrial and vacuolar marker enzymes. The protein-to-DNA ratios of the nuclei were 22 and 30 for CRY and CRX nuclei, respectively. An exopolyphosphatase (exopolyPase) with molecular mass of approximately 57 kDa and a pyrophosphatase (PPase) of approximately 41 kDa were detected in the parental strain CRY. Inactivation of PPX1 encoding a major exopolyPase (PPX1) in S. cerevisiae did not result in considerable changes in the content and properties of nuclear exopolyPase as compared to the parental strain of S. cerevisiae. Consequently, the nuclear exopolyPase was not encoded by PPX1. In the CRX strain, the exopolyPase was stimulated by bivalent metal cations. Co2+, the best activator, stimulated it by approximately 2.5-fold. The exopolyPase activity was nearly the same with polyphosphate (polyP) chain lengths ranging from 3 to 208 orthophosphate when measured with Mg2+. With Co 2+, the exopolyPase activity increased along with the increase in polymerization degree of the substrate.
authors.affiliation: Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Moscow Region, 142290, Pushchino, Russia. alla@ibpm.serpukhov.su
authors.forename: Lidia P
authors.initials: LP
authors.lastname: Lichko
authors.forename: Tatyana V
authors.initials: TV
authors.lastname: Kulakovskaya
authors.forename: Igor S
authors.initials: IS
authors.lastname: Kulaev
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D013379:Substrate Specificity; D014617:Vacuoles / Q000201:enzymology
chemical_list: D017766:Acid Anhydride Hydrolases; C020137:exopolyphosphatase