title: Mn2+ modulates the kinetic properties of an archaeal member of the PLL family.
abstract: Recently we reported on the characterization of an archaeal member of the amidohydrolase superfamily, namely Sulfolobus acidocaldarius lactonase, showing low but significant and extremely thermostable paraoxonase activity. This enzyme, that we have named SacPox, is a member of the new described family of phosphotriesterase-like lactonases (PLLs). In this family the binuclear metal centre, which is involved in the catalytic machinery, has been poorly studied up to now. In this work we describe the expression of the protein in presence of different metals showing Mn(2+) to support the higher activity. The enzyme has been over-expressed, purified and characterized as a Mn(2+)-containing enzyme by inductive plasma coupled mass spectrometry (ICP-MS), showing also surprising kinetic differences in comparison with the cadmium-containing enzyme. The Mn(2+) containing enzyme was about 30-fold more efficient with paraoxon as substrate and more stable than the Cd(2+) counterpart, even though the Mn(2+) affinity for the binuclear metal centre is apparently lower. These results increase our knowledge of the biochemical characteristics of SacPox mainly with regard to the metal-ions modulation of function.
authors.affiliation: Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via P Castellino 111, 80131 Naples, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Porzio
authors.forename: Spartaco
authors.initials: S
authors.lastname: Di Gennaro
authors.forename: Achille
authors.initials: A
authors.lastname: Palma
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Manco
mesh_terms: D001051:Apoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D015870:Gene Expression / Q000187:drug effects; D019766:Genes, Archaeal; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology*; D013058:Mass Spectrometry; D010261:Paraoxon / Q000378:metabolism; D044345:Phosphoric Triester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D016945:Sulfolobus acidocaldarius / Q000201:enzymology / Q000235:genetics; D013696:Temperature
chemical_list: D001051:Apoenzymes; D019843:Archaeal Proteins; D020035:Holoenzymes; D011994:Recombinant Proteins; D002104:Cadmium; D008345:Manganese; D002265:Carboxylic Ester Hydrolases; D044345:Phosphoric Triester Hydrolases; D010261:Paraoxon