title: Identification of an evolutionarily conserved family of inorganic polyphosphate endopolyphosphatases.
abstract: Inorganic polyphosphate (poly-P) consists of just a chain of phosphate groups linked by high energy bonds. It is found in every organism and is implicated in a wide variety of cellular processes (e.g. phosphate storage, blood coagulation, and pathogenicity). Its metabolism has been studied mainly in bacteria while remaining largely uncharacterized in eukaryotes. It has recently been suggested that poly-P metabolism is connected to that of highly phosphorylated inositol species (inositol pyrophosphates). Inositol pyrophosphates are molecules in which phosphate groups outnumber carbon atoms. Like poly-P they contain high energy bonds and play important roles in cell signaling. Here, we show that budding yeast mutants unable to produce inositol pyrophosphates have undetectable levels of poly-P. Our results suggest a prominent metabolic parallel between these two highly phosphorylated molecules. More importantly, we demonstrate that DDP1, encoding diadenosine and diphosphoinositol phosphohydrolase, possesses a robust poly-P endopolyphosphohydrolase activity. In addition, we prove that this is an evolutionarily conserved feature because mammalian Nudix hydrolase family members, the three Ddp1 homologues in human cells (DIPP1, DIPP2, and DIPP3), are also capable of degrading poly-P.
authors.affiliation: Medical Research Council Cell Biology Unit, Laboratory for Molecular Cell Biology, Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Lonetti
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szijgyarto
authors.forename: Daniel
authors.initials: D
authors.lastname: Bosch
authors.forename: Omar
authors.initials: O
authors.lastname: Loss
authors.forename: Cristina
authors.initials: C
authors.lastname: Azevedo
authors.forename: Adolfo
authors.initials: A
authors.lastname: Saiardi
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D043564:Inorganic Pyrophosphatase / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D011122:Polyphosphates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D011122:Polyphosphates; D029701:Saccharomyces cerevisiae Proteins; D043564:Inorganic Pyrophosphatase