title: Methanococcus jannaschii ORF mj0608 codes for a class C inorganic pyrophosphatase protected by Co(2+) or Mn(2+) ions against fluoride inhibition.
abstract: Openreading frame mj0608 of the Methanococcus jannaschii genome, recognized by its sequence similarity to that of the gene coding for class C inorganic pyrophosphatase in Bacillus subtilis, was cloned and over-expressed in Escherichia coli. The protein was purified and characterized by SDS-PAGE, M(r), and N-terminal sequence. Under suitable conditions it catalyzed the specific hydrolysis of PPi at about 600 micromol x min(-1) x mg(-1) at 25 degrees C, and at 8000 micromol x min(-1) x mg(-1) at 85 degrees C. Therefore this protein is a specific inorganic pyrophosphatase. The activities of Mg(2+), Mn(2+), Co(2+), and Zn(2+) ions as cofactors for hydrolysis of PPi were compared at pH 7.5 and 9.0. Unlike the class C pyrophosphatase of B. subtilis, this enzyme required no prior activation by low concentrations of Mn(2+) or Co(2+) ions. However, prior exposure to these ions afforded striking protection against inhibition by sodium fluoride, to which the enzyme was otherwise very sensitive.
authors.affiliation: School of Biosciences, The University of Birmingham, Birmingham, B15 2TT, United Kingdom. N.J.Kuhn@bham.ac.uk
authors.forename: N J
authors.initials: NJ
authors.lastname: Kuhn
authors.forename: A
authors.initials: A
authors.lastname: Wadeson
authors.forename: S
authors.initials: S
authors.lastname: Ward
authors.forename: T W
authors.initials: TW
authors.lastname: Young
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D002384:Catalysis / Q000187:drug effects; D002413:Cations, Divalent / Q000494:pharmacology*; D002614:Chelating Agents / Q000494:pharmacology; D011756:Diphosphates / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis / Q000187:drug effects; D043564:Inorganic Pyrophosphatase; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D017017:Methanococcus / Q000201:enzymology* / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017385:Sequence Homology; D012969:Sodium Fluoride / Q000494:pharmacology*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002413:Cations, Divalent; D002614:Chelating Agents; D011756:Diphosphates; D004791:Enzyme Inhibitors; D008670:Metals; D011994:Recombinant Proteins; D012969:Sodium Fluoride; D004492:Edetic Acid; D011755:Pyrophosphatases; D043564:Inorganic Pyrophosphatase