title: Cloning, expression, and characterization of thermotolerant manganese superoxide dismutase from Bacillus sp. MHS47.
abstract: A superoxide dismutase gene from thermotolerant Bacillus sp. MHS47 (MnSOD47) was cloned, sequenced, and expressed. The gene has an open reading frame of 612 bp, corresponding to 203 deduced amino acids, with high homology to the amino acid sequences of B. thuringiensis (accession no. EEN01322), B. anthracis (accession no. NP_846724), B. cereus (accession no. ZP_04187911), B. weihenstephanensis (accession no. YP_001646918), and B. pseudomycoides. The conserved manganese-binding sites (H28, H83, D165, and H169) show that MnSOD47 has the specific characteristics of the manganese superoxide dismutase (MnSOD) enzymes. MnSOD47 expressed an enzyme with a molecular weight of approximately 22.65 kDa and a specific activity of 3537.75 U/mg. The enzyme is active in the pH range 7-8.5, with an optimum pH of 7.5, and at temperatures in the range 30-45 °C, with an optimum temperature of 37 °C. Tests of inhibitors and metal ions indicated that the enzyme activity is inhibited by sodium azide, but not by hydrogen peroxide or potassium cyanide. These data should benefit future studies of MnSODs in other microorganisms and the biotechnological production of MnSOD47, and could also be used to develop a biosensor for the detection of antioxidants and free radical activity. In the future, this basic knowledge could be applicable to the detection of cancer risks in humans and therapeutic treatments.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok 10110, Thailand; E-Mails: jeedkha@hotmail.com (S.A.); pkhla@hotmail.com (P.K.); oom_arda@hotmail.com (A.P.).
authors.forename: Supatra
authors.initials: S
authors.lastname: Areekit
authors.forename: Pornpimon
authors.initials: P
authors.lastname: Kanjanavas
authors.forename: Paisarn
authors.initials: P
authors.lastname: Khawsak
authors.forename: Arda
authors.initials: A
authors.lastname: Pakpitchareon
authors.forename: Kajeenart
authors.initials: K
authors.lastname: Potivejkul
authors.forename: Gaysorn
authors.initials: G
authors.lastname: Chansiri
authors.forename: Kosum
authors.initials: K
authors.lastname: Chansiri
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D013482:Superoxide Dismutase